Problem in selecting the different fields from different text fields
hi,
Can anyone help me regarding my query.
i have 3 select list columns separately and what i m trying is that when i select one field from first select list the related fields must only be available for me in the second select list and so on.
Suppose i select EBSO as a product name from the first select list then only those thing should be visible to me in the second select list which is only related to EBSO only...and same wise with the third select list..
If anyone has the clue for this pls help me.
The only clue which i m finding is that to use the java scrpts but how to use is another difficulty for me.
Regards
I will explain this through an example.
In my application I have created two Select Lists.
The first select list is a select list with a submit
P3_X allows selection of 1,2,3
The page branch sets the value of P3_X with &P3_X. so that way the second select list knows what value it will be using.
The second select list P3_Y is a dynamic query that says
Select SCOL d, SCOL r from TEST1 where FCOL=:P3_X
If you were to have a third select list you would make the second Select List also a submit and have the page branch also set P3_Y with &P3_Y.
The third Select list would say select from where item=:P3_Y
Does this answer your question?
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I am currently using the iPhone to record my vocals on top of professional beats, or riddims as they are called in the dancehall world. Is there a way for me to select multipe voice sections from different tracks, copy them and then paste them later in the project. I don't want to record the chorus more than once. Normally what I do is sync the project to my wife MacBook Air and then from there edit it but I would like to avoid this. Also, I use the earpods microphone to record my voice and of course it doesn't come out professional quality but it is decent. Do you recommend a microphone that plugs to the iPhone or should I get an interface? Thanks for the help.
You can either copy and paste single regions or duplicate sections, if you want to copy regions
from different tracks in parallel.
See: Extend a song with song sections
Adjust the length of your sections in a way, that the regions you want to copy from different tracks are together in a section of your song.
Add a copy of a section:
Open the song section controls, choose the section you want to copy, then tap Duplicate.The copy is added after the last section.
Tap Done to close the song section controls.
After copying the section, move the new section to the end of the song:
Change the order of sections:
Open the song section controls, then tap Edit.
Drag a section up or down in the list by the handle on its right edge.
When you are finished, tap Done.
Tap Done to close the song section controls.
Regards
Léonie -
How to join fields from different internal tables and display into one int
hai i have one doubt...
how to join fields from different internal tables and display into one internal table..
if anybody know the ans for this qus tell me......hii
you can read data as per condition and then can join in one internal table using READ and APPEND statement..refer to following code.
SELECT bwkey " Valuation Area
bukrs " Company Code
FROM t001k
INTO TABLE i_t001k
WHERE bukrs IN s_bukrs.
IF sy-subrc EQ 0.
SELECT bwkey " Valuation Area
werks " Plant
FROM t001w
INTO TABLE i_t001w
FOR ALL ENTRIES IN i_t001k
WHERE bwkey = i_t001k-bwkey
AND werks IN s_werks.
IF sy-subrc EQ 0.
LOOP AT i_output INTO wa_output.
READ TABLE i_t001w INTO wa_t001w WITH KEY werks = wa_output-werks.
READ TABLE i_t001k INTO wa_t001k WITH KEY bwkey = wa_t001w-bwkey.
wa_output-bukrs = wa_t001k-bukrs.
MODIFY i_output FROM wa_output.
CLEAR wa_output.
ENDLOOP. " LOOP AT i_output
ENDIF. " IF sy-subrc EQ 0
regards
twinkal -
Does anyone have experience with having multiple editors work on the same project from different computers?
As much as I hate to admit it, YOU ARE RIGHT!
I will tread lightly on this project.
Thanks for the sanity check,
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction -
I want to add multiples of the same song from different playlists to my ipod but iTunes wont let me. How can I override this so that I get the songs I want on my ipod?
You can sync those different playlists to the iPod, and the song appears on each playlist. However, the song is stored on the iPod once. What is the practical reason for wanting to store the same song file multiple times (and waste storage space) on the iPod?
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How to select the data efficiently from the table
hi every one,
i need some help in selecting data from FAGLFLEXA table.i have to select many amounts from different group of G/L accounts
(groups are predefined here which contains a set of g/L account no.).
if i select every time for each group then it will be a performance issue, in order to avoid it what should i do, can any one suggest me a method or a smaple query so that i can perform the task efficiently.Hi ,
1.select and keep the data in internal table
2.avoid select inside loop ..endloop.
3.try to use for all entries
check the below details
Hi Praveen,
Performance Notes
1.Keep the Result Set Small
You should aim to keep the result set small. This reduces both the amount of memory used in the database system and the network load when transferring data to the application server. To reduce the size of your result sets, use the WHERE and HAVING clauses.
Using the WHERE Clause
Whenever you access a database table, you should use a WHERE clause in the corresponding Open SQL statement. Even if a program containing a SELECT statement with no WHERE clause performs well in tests, it may slow down rapidly in your production system, where the data volume increases daily. You should only dispense with the WHERE clause in exceptional cases where you really need the entire contents of the database table every time the statement is executed.
When you use the WHERE clause, the database system optimizes the access and only transfers the required data. You should never transfer unwanted data to the application server and then filter it using ABAP statements.
Using the HAVING Clause
After selecting the required lines in the WHERE clause, the system then processes the GROUP BY clause, if one exists, and summarizes the database lines selected. The HAVING clause allows you to restrict the grouped lines, and in particular, the aggregate expressions, by applying further conditions.
Effect
If you use the WHERE and HAVING clauses correctly:
There are no more physical I/Os in the database than necessary
No unwanted data is stored in the database cache (it could otherwise displace data that is actually required)
The CPU usage of the database host is minimize
The network load is reduced, since only the data that is required by the application is transferred to the application server.
Minimize the Amount of Data Transferred
Data is transferred between the database system and the application server in blocks. Each block is up to 32 KB in size (the precise size depends on your network communication hardware). Administration information is transported in the blocks as well as the data.
To minimize the network load, you should transfer as few blocks as possible. Open SQL allows you to do this as follows:
Restrict the Number of Lines
If you only want to read a certain number of lines in a SELECT statement, use the UP TO <n> ROWS addition in the FROM clause. This tells the database system only to transfer <n> lines back to the application server. This is more efficient than transferring more lines than necessary back to the application server and then discarding them in your ABAP program.
If you expect your WHERE clause to return a large number of duplicate entries, you can use the DISTINCT addition in the SELECT clause.
Restrict the Number of Columns
You should only read the columns from a database table that you actually need in the program. To do this, list the columns in the SELECT clause. Note here that the INTO CORRESPONDING FIELDS addition in the INTO clause is only efficient with large volumes of data, otherwise the runtime required to compare the names is too great. For small amounts of data, use a list of variables in the INTO clause.
Do not use * to select all columns unless you really need them. However, if you list individual columns, you may have to adjust the program if the structure of the database table is changed in the ABAP Dictionary. If you specify the database table dynamically, you must always read all of its columns.
Use Aggregate Functions
If you only want to use data for calculations, it is often more efficient to use the aggregate functions of the SELECT clause than to read the individual entries from the database and perform the calculations in the ABAP program.
Aggregate functions allow you to find out the number of values and find the sum, average, minimum, and maximum values.
Following an aggregate expression, only its result is transferred from the database.
Data Transfer when Changing Table Lines
When you use the UPDATE statement to change lines in the table, you should use the WHERE clause to specify the relevant lines, and then SET statements to change only the required columns.
When you use a work area to overwrite table lines, too much data is often transferred. Furthermore, this method requires an extra SELECT statement to fill the work area. Minimize the Number of Data Transfers
In every Open SQL statement, data is transferred between the application server and the database system. Furthermore, the database system has to construct or reopen the appropriate administration data for each database access. You can therefore minimize the load on the network and the database system by minimizing the number of times you access the database.
Multiple Operations Instead of Single Operations
When you change data using INSERT, UPDATE, and DELETE, use internal tables instead of single entries. If you read data using SELECT, it is worth using multiple operations if you want to process the data more than once, other wise, a simple select loop is more efficient.
Avoid Repeated Access
As a rule you should read a given set of data once only in your program, and using a single access. Avoid accessing the same data more than once (for example, SELECT before an UPDATE).
Avoid Nested SELECT Loops
A simple SELECT loop is a single database access whose result is passed to the ABAP program line by line. Nested SELECT loops mean that the number of accesses in the inner loop is multiplied by the number of accesses in the outer loop. You should therefore only use nested SELECT loops if the selection in the outer loop contains very few lines.
However, using combinations of data from different database tables is more the rule than the exception in the relational data model. You can use the following techniques to avoid nested SELECT statements:
ABAP Dictionary Views
You can define joins between database tables statically and systemwide as views in the ABAP Dictionary. ABAP Dictionary views can be used by all ABAP programs. One of their advantages is that fields that are common to both tables (join fields) are only transferred once from the database to the application server.
Views in the ABAP Dictionary are implemented as inner joins. If the inner table contains no lines that correspond to lines in the outer table, no data is transferred. This is not always the desired result. For example, when you read data from a text table, you want to include lines in the selection even if the corresponding text does not exist in the required language. If you want to include all of the data from the outer table, you can program a left outer join in ABAP.
The links between the tables in the view are created and optimized by the database system. Like database tables, you can buffer views on the application server. The same buffering rules apply to views as to tables. In other words, it is most appropriate for views that you use mostly to read data. This reduces the network load and the amount of physical I/O in the database.
Joins in the FROM Clause
You can read data from more than one database table in a single SELECT statement by using inner or left outer joins in the FROM clause.
The disadvantage of using joins is that redundant data is read from the hierarchically-superior table if there is a 1:N relationship between the outer and inner tables. This can considerably increase the amount of data transferred from the database to the application server. Therefore, when you program a join, you should ensure that the SELECT clause contains a list of only the columns that you really need. Furthermore, joins bypass the table buffer and read directly from the database. For this reason, you should use an ABAP Dictionary view instead of a join if you only want to read the data.
The runtime of a join statement is heavily dependent on the database optimizer, especially when it contains more than two database tables. However, joins are nearly always quicker than using nested SELECT statements.
Subqueries in the WHERE and HAVING Clauses
Another way of accessing more than one database table in the same Open SQL statement is to use subqueries in the WHERE or HAVING clause. The data from a subquery is not transferred to the application server. Instead, it is used to evaluate conditions in the database system. This is a simple and effective way of programming complex database operations.
Using Internal Tables
It is also possible to avoid nested SELECT loops by placing the selection from the outer loop in an internal table and then running the inner selection once only using the FOR ALL ENTRIES addition. This technique stems from the time before joins were allowed in the FROM clause. On the other hand, it does prevent redundant data from being transferred from the database.
Using a Cursor to Read Data
A further method is to decouple the INTO clause from the SELECT statement by opening a cursor using OPEN CURSOR and reading data line by line using FETCH NEXT CURSOR. You must open a new cursor for each nested loop. In this case, you must ensure yourself that the correct lines are read from the database tables in the correct order. This usually requires a foreign key relationship between the database tables, and that they are sorted by the foreign key. Minimize the Search Overhead
You minimize the size of the result set by using the WHERE and HAVING clauses. To increase the efficiency of these clauses, you should formulate them to fit with the database table indexes.
Database Indexes
Indexes speed up data selection from the database. They consist of selected fields of a table, of which a copy is then made in sorted order. If you specify the index fields correctly in a condition in the WHERE or HAVING clause, the system only searches part of the index (index range scan).
The primary index is always created automatically in the R/3 System. It consists of the primary key fields of the database table. This means that for each combination of fields in the index, there is a maximum of one line in the table. This kind of index is also known as UNIQUE.
If you cannot use the primary index to determine the result set because, for example, none of the primary index fields occur in the WHERE or HAVING clause, the system searches through the entire table (full table scan). For this case, you can create secondary indexes, which can restrict the number of table entries searched to form the result set.
You specify the fields of secondary indexes using the ABAP Dictionary. You can also determine whether the index is unique or not. However, you should not create secondary indexes to cover all possible combinations of fields.
Only create one if you select data by fields that are not contained in another index, and the performance is very poor. Furthermore, you should only create secondary indexes for database tables from which you mainly read, since indexes have to be updated each time the database table is changed. As a rule, secondary indexes should not contain more than four fields, and you should not have more than five indexes for a single database table.
If a table has more than five indexes, you run the risk of the optimizer choosing the wrong one for a particular operation. For this reason, you should avoid indexes with overlapping contents.
Secondary indexes should contain columns that you use frequently in a selection, and that are as highly selective as possible. The fewer table entries that can be selected by a certain column, the higher that columns selectivity. Place the most selective fields at the beginning of the index. Your secondary index should be so selective that each index entry corresponds to at most five percent of the table entries. If this is not the case, it is not worth creating the index. You should also avoid creating indexes for fields that are not always filled, where their value is initial for most entries in the table.
If all of the columns in the SELECT clause are contained in the index, the system does not have to search the actual table data after reading from the index. If you have a SELECT clause with very few columns, you can improve performance dramatically by including these columns in a secondary index.
Formulating Conditions for Indexes
You should bear in mind the following when formulating conditions for the WHERE and HAVING clauses so that the system can use a database index and does not have to use a full table scan.
Check for Equality and Link Using AND
The database index search is particularly efficient if you check all index fields for equality (= or EQ) and link the expressions using AND.
Use Positive Conditions
The database system only supports queries that describe the result in positive terms, for example, EQ or LIKE. It does not support negative expressions like NE or NOT LIKE.
If possible, avoid using the NOT operator in the WHERE clause, because it is not supported by database indexes; invert the logical expression instead.
Using OR
The optimizer usually stops working when an OR expression occurs in the condition. This means that the columns checked using OR are not included in the index search. An exception to this are OR expressions at the outside of conditions. You should try to reformulate conditions that apply OR expressions to columns relevant to the index, for example, into an IN condition.
Using Part of the Index
If you construct an index from several columns, the system can still use it even if you only specify a few of the columns in a condition. However, in this case, the sequence of the columns in the index is important. A column can only be used in the index search if all of the columns before it in the index definition have also been specified in the condition.
Checking for Null Values
The IS NULL condition can cause problems with indexes. Some database systems do not store null values in the index structure. Consequently, this field cannot be used in the index.
Avoid Complex Conditions
Avoid complex conditions, since the statements have to be broken down into their individual components by the database system.
Reduce the Database Load
Unlike application servers and presentation servers, there is only one database server in your system. You should therefore aim to reduce the database load as much as possible. You can use the following methods:
Buffer Tables on the Application Server
You can considerably reduce the time required to access data by buffering it in the application server table buffer. Reading a single entry from table T001 can take between 8 and 600 milliseconds, while reading it from the table buffer takes 0.2 - 1 milliseconds.
Whether a table can be buffered or not depends its technical attributes in the ABAP Dictionary. There are three buffering types:
Resident buffering (100%) The first time the table is accessed, its entire contents are loaded in the table buffer.
Generic buffering In this case, you need to specify a generic key (some of the key fields) in the technical settings of the table in the ABAP Dictionary. The table contents are then divided into generic areas. When you access data with one of the generic keys, the whole generic area is loaded into the table buffer. Client-specific tables are often buffered generically by client.
Partial buffering (single entry) Only single entries are read from the database and stored in the table buffer.
When you read from buffered tables, the following happens:
1. An ABAP program requests data from a buffered table.
2. The ABAP processor interprets the Open SQL statement. If the table is defined as a buffered table in the ABAP Dictionary, the ABAP processor checks in the local buffer on the application server to see if the table (or part of it) has already been buffered.
3. If the table has not yet been buffered, the request is passed on to the database. If the data exists in the buffer, it is sent to the program.
4. The database server passes the data to the application server, which places it in the table buffer.
5. The data is passed to the program.
When you change a buffered table, the following happens:
1. The database table is changed and the buffer on the application server is updated. The database interface logs the update statement in the table DDLOG. If the system has more than one application server, the buffer on the other servers is not updated at once.
2. All application servers periodically read the contents of table DDLOG, and delete the corresponding contents from their buffers where necessary. The granularity depends on the buffering type. The table buffers in a distributed system are generally synchronized every 60 seconds (parameter: rsdisp/bufreftime).
3. Within this period, users on non-synchronized application servers will read old data. The data is not recognized as obsolete until the next buffer synchronization. The next time it is accessed, it is re-read from the database.
You should buffer the following types of tables:
Tables that are read very frequently
Tables that are changed very infrequently
Relatively small tables (few lines, few columns, or short columns)
Tables where delayed update is acceptable.
Once you have buffered a table, take care not to use any Open SQL statements that bypass the buffer.
The SELECT statement bypasses the buffer when you use any of the following:
The BYPASSING BUFFER addition in the FROM clause
The DISTINCT addition in the SELECT clause
Aggregate expressions in the SELECT clause
Joins in the FROM clause
The IS NULL condition in the WHERE clause
Subqueries in the WHERE clause
The ORDER BY clause
The GROUP BY clause
The FOR UPDATE addition
Furthermore, all Native SQL statements bypass the buffer.
Avoid Reading Data Repeatedly
If you avoid reading the same data repeatedly, you both reduce the number of database accesses and reduce the load on the database. Furthermore, a "dirty read" may occur with database tables other than Oracle. This means that the second time you read data from a database table, it may be different from the data read the first time. To ensure that the data in your program is consistent, you should read it once only and then store it in an internal table.
Sort Data in Your ABAP Programs
The ORDER BY clause in the SELECT statement is not necessarily optimized by the database system or executed with the correct index. This can result in increased runtime costs. You should only use ORDER BY if the database sort uses the same index with which the table is read. To find out which index the system uses, use SQL Trace in the ABAP Workbench Performance Trace. If the indexes are not the same, it is more efficient to read the data into an internal table or extract and sort it in the ABAP program using the SORT statement.
Use Logical Databases
SAP supplies logical databases for all applications. A logical database is an ABAP program that decouples Open SQL statements from application programs. They are optimized for the best possible database performance. However, it is important that you use the right logical database. The hierarchy of the data you want to read must reflect the structure of the logical database, otherwise, they can have a negative effect on performance. For example, if you want to read data from a table right at the bottom of the hierarchy of the logical database, it has to read at least the key fields of all tables above it in the hierarchy. In this case, it is more efficient to use a SELECT statement.
Work Processes
Work processes execute the individual dialog steps in R/3 applications. The next two sections describe firstly the structure of a work process, and secondly the different types of work process in the R/3 System.
Structure of a Work Process
Work processes execute the dialog steps of application programs. They are components of an application server. The following diagram shows the components of a work process:
Each work process contains two software processors and a database interface.
Screen Processor
In R/3 application programming, there is a difference between user interaction and processing logic. From a programming point of view, user interaction is controlled by screens. As well as the actual input mask, a screen also consists of flow logic. The screen flow logic controls a large part of the user interaction. The R/3 Basis system contains a special language for programming screen flow logic. The screen processor executes the screen flow logic. Via the dispatcher, it takes over the responsibility for communication between the work process and the SAPgui, calls modules in the flow logic, and ensures that the field contents are transferred from the screen to the flow logic.
ABAP Processor
The actual processing logic of an application program is written in ABAP - SAPs own programming language. The ABAP processor executes the processing logic of the application program, and communicates with the database interface. The screen processor tells the ABAP processor which module of the screen flow logic should be processed next. The following screen illustrates the interaction between the screen and the ABAP processors when an application program is running.
Database Interface
The database interface provides the following services:
Establishing and terminating connections between the work process and the database.
Access to database tables
Access to R/3 Repository objects (ABAP programs, screens and so on)
Access to catalog information (ABAP Dictionary)
Controlling transactions (commit and rollback handling)
Table buffer administration on the application server.
The following diagram shows the individual components of the database interface:
The diagram shows that there are two different ways of accessing databases: Open SQL and Native SQL.
Open SQL statements are a subset of Standard SQL that is fully integrated in ABAP. They allow you to access data irrespective of the database system that the R/3 installation is using. Open SQL consists of the Data Manipulation Language (DML) part of Standard SQL; in other words, it allows you to read (SELECT) and change (INSERT, UPDATE, DELETE) data. The tasks of the Data Definition Language (DDL) and Data Control Language (DCL) parts of Standard SQL are performed in the R/3 System by the ABAP Dictionary and the authorization system. These provide a unified range of functions, irrespective of database, and also contain functions beyond those offered by the various database systems.
Open SQL also goes beyond Standard SQL to provide statements that, in conjunction with other ABAP constructions, can simplify or speed up database access. It also allows you to buffer certain tables on the application server, saving excessive database access. In this case, the database interface is responsible for comparing the buffer with the database. Buffers are partly stored in the working memory of the current work process, and partly in the shared memory for all work processes on an application server. Where an R/3 System is distributed across more than one application server, the data in the various buffers is synchronized at set intervals by the buffer management. When buffering the database, you must remember that data in the buffer is not always up to date. For this reason, you should only use the buffer for data which does not often change.
Native SQL is only loosely integrated into ABAP, and allows access to all of the functions contained in the programming interface of the respective database system. Unlike Open SQL statements, Native SQL statements are not checked and converted, but instead are sent directly to the database system. Programs that use Native SQL are specific to the database system for which they were written. R/3 applications contain as little Native SQL as possible. In fact, it is only used in a few Basis components (for example, to create or change table definitions in the ABAP Dictionary).
The database-dependent layer in the diagram serves to hide the differences between database systems from the rest of the database interface. You choose the appropriate layer when you install the Basis system. Thanks to the standardization of SQL, the differences in the syntax of statements are very slight. However, the semantics and behavior of the statements have not been fully standardized, and the differences in these areas can be greater. When you use Native SQL, the function of the database-dependent layer is minimal.
Types of Work Process
Although all work processes contain the components described above, they can still be divided into different types. The type of a work process determines the kind of task for which it is responsible in the application server. It does not specify a particular set of technical attributes. The individual tasks are distributed to the work processes by the dispatcher.
Before you start your R/3 System, you determine how many work processes it will have, and what their types will be. The dispatcher starts the work processes and only assigns them tasks that correspond to their type. This means that you can distribute work process types to optimize the use of the resources on your application servers.
The following diagram shows again the structure of an application server, but this time, includes the various possible work process types:
The various work processes are described briefly below. Other parts of this documentation describe the individual components of the application server and the R/3 System in more detail.
Dialog Work Process
Dialog work processes deal with requests from an active user to execute dialog steps.
Update Work Process
Update work processes execute database update requests. Update requests are part of an SAP LUW that bundle the database operations resulting from the dialog in a database LUW for processing in the background.
Background Work Process
Background work processes process programs that can be executed without user interaction (background jobs).
Enqueue Work Process
The enqueue work process administers a lock table in the shared memory area. The lock table contains the logical database locks for the R/3 System and is an important part of the SAP LUW concept. In an R/3 System, you may only have one lock table. You may therefore also only have one application server with enqueue work processes.
Spool Work Process
The spool work process passes sequential datasets to a printer or to optical archiving. Each application server may contain several spool work process.
The services offered by an application server are determined by the types of its work processes. One application server may, of course, have more than one function. For example, it may be both a dialog server and the enqueue server, if it has several dialog work processes and an enqueue work process.
You can use the system administration functions to switch a work process between dialog and background modes while the system is still running. This allows you, for example, to switch an R/3 System between day and night operation, where you have more dialog than background work processes during the day, and the other way around during the night.
ABAP Application Server
R/3 programs run on application servers. They are an important component of the R/3 System. The following sections describe application servers in more detail.
Structure of an ABAP Application Server
The application layer of an R/3 System is made up of the application servers and the message server. Application programs in an R/3 System are run on application servers. The application servers communicate with the presentation components, the database, and also with each other, using the message server.
The following diagram shows the structure of an application server:
The individual components are:
Work Processes
An application server contains work processes, which are components that can run an application. Work processes are components that are able to execute an application (that is, one dialog step each). Each work process is linked to a memory area containing the context of the application being run. The context contains the current data for the application program. This needs to be available in each dialog step. Further information about the different types of work process is contained later on in this documentation.
Dispatcher
Each application server contains a dispatcher. The dispatcher is the link between the work processes and the users logged onto the application server. Its task is to receive requests for dialog steps from the SAP GUI and direct them to a free work process. In the same way, it directs screen output resulting from the dialog step back to the appropriate user.
Gateway
Each application server contains a gateway. This is the interface for the R/3 communication protocols (RFC, CPI/C). It can communicate with other application servers in the same R/3 System, with other R/3 Systems, with R/2 Systems, or with non-SAP systems.
The application server structure as described here aids the performance and scalability of the entire R/3 System. The fixed number of work processes and dispatching of dialog steps leads to optimal memory use, since it means that certain components and the memory areas of a work process are application-independent and reusable. The fact that the individual work processes work independently makes them suitable for a multi-processor architecture. The methods used in the dispatcher to distribute tasks to work processes are discussed more closely in the section Dispatching Dialog Steps.
Shared Memory
All of the work processes on an application server use a common main memory area called shared memory to save contexts or to buffer constant data locally.
The resources that all work processes use (such as programs and table contents) are contained in shared memory. Memory management in the R/3 System ensures that the work processes always address the correct context, that is the data relevant to the current state of the program that is running. A mapping process projects the required context for a dialog step from shared memory into the address of the relevant work process. This reduces the actual copying to a minimum.
Local buffering of data in the shared memory of the application server reduces the number of database reads required. This reduces access times for application programs considerably. For optimal use of the buffer, you can concentrate individual applications (financial accounting, logistics, human resources) into separate application server groups.
Database Connection
When you start up an R/3 System, each application server registers its work processes with the database layer, and receives a single dedicated channel for each. While the system is running, each work process is a user (client) of the database system (server). You cannot change the work process registration while the system is running. Neither can you reassign a database channel from one work process to another. For this reason, a work process can only make database changes within a single database logical unit of work (LUW). A database LUW is an inseparable sequence of database operations. This has important consequences for the programming model explained below.
Dispatching Dialog Steps
The number of users logged onto an application server is often many times greater than the number of available work processes. Furthermore, it is not restricted by the R/3 system architecture. Furthermore, each user can run several applications at once. The dispatcher has the important task of distributing all dialog steps among the work processes on the application server.
The following diagram is an example of how this might happen:
1. The dispatcher receives the request to execute a dialog step from user 1 and directs it to work process 1, which happens to be free. The work process addresses the context of the application program (in shared memory) and executes the dialog step. It then becomes free again.
2. The dispatcher receives the request to execute a dialog step from user 2 and directs it to work process 1, which is now free again. The work process executes the dialog step as in step 1.
3. While work process 1 is still working, the dispatcher receives a further request from user 1 and directs it to work process 2, which is free.
4. After work processes 1 and 2 have finished processing their dialog steps, the dispatcher receives another request from user 1 and directs it to work process 1, which is free again.
5. While work process 1 is still working, the dispatcher receives a further request from user 2 and directs it to work process 2, which is free.
From this example, we can see that:
A dialog step from a program is assigned to a single work process for execution.
The individual dialog steps of a program can be executed on different work processes, and the program context must be addressed for each new work process.
A work process can execute dialog steps of different programs from different users.
The example does not show that the dispatcher tries to distribute the requests to the work processes such that the same work process is used as often as possible for the successive dialog steps in an application. This is useful, since it saves the program context having to be addressed each time a dialog step is executed.
Dispatching and the Programming Model
The separation of application and presentation layer made it necessary to split up application programs into dialog steps. This, and the fact that dialog steps are dispatched to individual work processes, has had important consequences for the programming model.
As mentioned above, a work process can only make database changes within a single database logical unit of work (LUW). A database LUW is an inseparable sequence of database operations. The contents of the database must be consistent at its beginning and end. The beginning and end of a database LUW are defined by a commit command to the database system (database commit). During a database LUW, that is, between two database commits, the database system itself ensures consistency within the database. In other words, it takes over tasks such as locking database entries while they are being edited, or restoring the old data (rollback) if a step terminates in an error.
A typical SAP application program extends over several screens and the corresponding dialog steps. The user requests database changes on the individual screens that should lead to the database being consistent once the screens have all been processed. However, the individual dialog steps run on different work processes, and a single work process can process dialog steps from other applications. It is clear that two or more independent applications whose dialog steps happen to be processed on the same work process cannot be allowed to work with the same database LUW.
Consequently, a work process must open a separate database LUW for each dialog step. The work process sends a commit command (database commit) to the database at the end of each dialog step in which it makes database changes. These commit commands are called implicit database commits, since they are not explicitly written into the application program.
These implicit database commits mean that a database LUW can be kept open for a maximum of one dialog step. This leads to a considerable reduction in database load, serialization, and deadlocks, and enables a large number of users to use the same system.
However, the question now arises of how this method (1 dialog step = 1 database LUW) can be reconciled with the demand to make commits and rollbacks dependent on the logical flow of the application program instead of the technical distribution of dialog steps. Database update requests that depend on one another form logical units in the program that extend over more than one dialog step. The database changes associated with these logical units must be executed together and must also be able to be undone together.
The SAP programming model contains a series of bundling techniques that allow you to group database updates together in logical units. The section of an R/3 application program that bundles a set of logically-associated database operations is called an SAP LUW. Unlike a database LUW, a SAP LUW includes all of the dialog steps in a logical unit, including the database update.
Happy Reading...
shibu -
Problem with: select 'c' as X from dual
Problem with 'select 'c' as X from dual'
I get 2 different results when I execute the above with SQLPlus (or java) depending on the instance I am connected to. For one instance the result is a single character and for the other the character is padded with blanks to 32 chars in the SQLPlus window (and java). Does anyone know what database setting causes this to happen? Is it a version issue ?
Test #1: Oracle 9.2.0.6 - SQLPlus result is padded with blanks
SQL*Plus: Release 9.2.0.1.0 - Production on Mon Dec 10 09:27:58 2007
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.6.0 - 64bit Production
With the Partitioning option
JServer Release 9.2.0.6.0 - Production
SQL> select 'c' as X from dual;
X
c
SQL>
Test #2 Oracle 9.2.0.1 SQLPlus result is a single character.
SQL*Plus: Release 9.2.0.1.0 - Production on Mon Dec 10 09:29:27 2007
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
SQL> select 'c' as X from dual;
X
c
SQL>Using 9.2.0.6 On AIX 5.2 I get the single byte result:
UT1 > select 'c' as X from dual;
X
c
If the databases are on different Oracle Homes you may want to check the sqlplus global logon files for any set commands.
If you executed the two sql statements from different OS directories you may also want to check your sqlpath for sqlplus .logon files.
Try issueing clear columns and repeating the statement. Are the results the same?
HTH -- Mark D Powell -- -
Problem in getting the database connection from a connection pool
Hai All,
I am facing a problem in getting the database connection from a connection pool created on weblogic server 8.1.
I am using the Oracle database 8.1.7.
I have configured my connection pool, datasource and JNDI in weblogic.
In my java program i have the following code to retrieve the connection.
import java.sql.*;
import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.InitialContext;
class jdbcshp1 {
public static void main(String[] args) {
Connection connection = null;
try {
Hashtable ht = new Hashtable();
ht.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory"); // Wanna get rid of this.
ht.put(Context.PROVIDER_URL,"t3://localhost:7001"); // wanna get rid of this.
// Get a context for the JNDI look up
Context ctx = new InitialContext(ht);
javax.sql.DataSource ds = (javax.sql.DataSource) ctx.lookup ("myjndi1");
//Create a connection object
connection = ds.getConnection();
The above code is working fine but, the two ht.put statements are creating problem.
The problem is, after converting the application into WAR file it can be deployed
on any machine or different port on same machine. My application fails if its deployed on
weglogicserver which is at different port.
Is there any way that i can get rid of those ht.put statements or any other way to solve the problem.
any help is appreciated.
Thanks in advance
Pooja.Hai All,
Firstly, thanks for ur reply.
Even i have seen some code which uses context constructor with out any parameter and works fine.
i dont understand why its not working for my code.
When i remove those ht.put code and use context constructor with out any parameter, it giving an error.
Context ctx = new InitialContext();
javax.sql.DataSource ds = (javax.sql.DataSource) ctx.lookup ("ocjndi");
connection = ds.getConnection();The error is as follows:
javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or as an applet parameter, or in an application resource file: java.naming.factory.initial
the above error is forcing me to include those code but if the port number is changed the code will not work. Plz let meknow if some setting have to be made.
I appreciate all ur valuable help.
Thanks once again.
Pooja. -
I can´t remove windows partition from my mac because I´can´t select the remove option from boot camp assit. Can any body help me?
open disc utility choose the drive you need partitioning highlight the bootcamp partition and click on the minus sign at the bottom left.
after this manually resize your drive by dragging the partition line all the way down and click on partition. -
Hello,
I have a strange issue on my Windows 8.1 machine. The icon for for an executable file on the network shows blank, if I select the second icon from the library. (File->Properties->Change Icon and select the second icon - This file has two icons)
If I re-create the IconCache.db, then it is showing correctly. But I do not want to do this every time.
Regards
MattehwIt indicates your Icon Cache is corrupted and you need to rebuild it.
Open the command prompt window, type each of the following and after every command, hit the Enter button:
cd /d %userprofile%\AppData\Local
attrib –h IconCache.db
del IconCache.db
start explorer
S.Sengupta, Windows Entertainment and Connected Home MVP -
How to select the max rowid from a subquery with group by
Hi Gurus,
Kindly help how to fix the following query because I'm getting Oracle error:ORA-01446.
select * from edy_raw_data a
where rowid in ( select max(rowid) from(
select email,max(date_updated) from edy_raw_data b
where b.email=a.email
group by email ))
The query select the max rowid from a sub query with group by.
Thanks in Advance.
BenjieWhy do you need to compare with rowid?
Wouldn't this suffice?
select * from edy_raw_data a
where (email,date_updated) = (select email, max(date_updated) from edy_raw_data b
where b.email=a.email
group by b.email ))* Note: untested -
Linking a select field with a text field in a DW form.....
I did try to search for this but nothing came to my attention. Apologies if it is already in the forum.
Is it possible to have a "select field" link with a "text field"? In other words The select field will provide different venues to choose from, in this case "Blog, Trade Show, Friend, Photo Magazine" and then after the choice is made a text field appears that allows you to provide details re. your choice. For example if you choose "Trade Show" from the select field the text field will then appear and prompt you to detail WHICH Trade Show. Something along those lines. Any assistance will, as always, be appreciated.
-G-You need scripts for this. Try this jQuery tutorial
http://anthonygthomas.com/2010/03/14/display-form-fields-based-on-selection-using-jquery/
Nancy O. -
Populate drop-down list from multiple text fields.
Just to begin, I am brand new to this application and brand new to coding in general. Anyways, this is what I am trying to accomplish. I need to populate a drop-down list from multiple text fields. I am able to populate one item using this in the calculate event:
TextField1.rawValue
After I type text in TextField1 and hit enter, it displays the text in the drop-down list. I need to do this but with more than just one text field to populate more options for the drop-down list. I will also need to do something similar with populating a drop-down list from selections made in multiple other drop-down lists.
Thanks for any help you can give me.Thank you for your suggestion Geo Kaiser. With that, I was able to populate my drop-down lists, but now when I select an option from the drop-down list, the selection dissapears. The selection will appear briefly in the box but then dissapears although my drop-down list options remain there. Here is the code I am using for my text field to drop-down list:
DropDownList1.clearItems()
DropDownList1.addItem(TextField1)
DropDownList1.addItem(TextField2)
And here is my code for my drop-down list to populate another drop-down list:
DropDownList3.clearItems()
DropDownList3.addItem(DropDownList1)
DropDownList3.additem(DropDownList2)
Thanks again for your help. By the way, I am using Adobe Designer 7.0. -
How to provide text formatting options to user from a text field
Hi,
My requirement is - in the interactive form, a comments field needs to be provided where user should be able to enter text with formatting options like
Headers
indentations
bold/italic
bullet points and numbers
Once user enters the formatted texts in a text field, data needs to be displayed/printed in the same format. Could you help me on how to provide these formatting options to the user for a particular text field?
I understand that once I define the text field with format XHTML (with RTF), user formatting can be captured and displayed in the same way. But I am not sure on how to provide the formatting options for the text field.
Thank you,
MadhuHi,
if you select a text field for Rich Text and the press Ctrl + E you'll get a bar for all available text formatting options in Acrobat/Reader. -
How to set the Background Color of a Text Field in a Tabular Report.
Hello,
I tried to set the Background Color of a Text Field in a Tabular Report.
But I was not able to change this colur.
In the report attributes --> column attributes
I tried already:
1. Column Formating -- >CSS Style (bgcolor: red)
2. Tabular Form Element --> Element Attributes (bgcolor: red)
but nothing worked.
Can anybody help me?
I Use Oracle Apex 2.2.1 on 10gR2
thank you in advance.
Oliverin "Report Attributes" select the column to move to the "Column Attributes" page. In the "Element Attributes" field under the "Tabular Form Element" region enter
style="background-color:red;"
I will also check if there is a way to do this via the template and post here again
edit:
in your template definition, above the template, enter the following:
< STYLE TYPE="text/css" >
.class INPUT {background-color:red;}
< /STYLE >
(remove the spaces after the < and before the >)
change "class" to the class that the template is calling
(I'm using theme 9, the table has: class="t9GCCReportsStyle1" so I would enter t9GCCReportsStyle1)
A side-effect of using this second version is that ALL input types will have a red background color--checkboxes, input boxes, etc.
Message was edited by:
TheJosh -
Reading fields from a text file
Hi, I'm fairly new to this so bear with me.
This is for an assignment - the idea is to cretae an online system for booking seats at a cinema - haven't got past the login stage yet?
I've got an applet that needs to read in a field from a text file.
I'm using the StringTokenizer function.
I've put a test in to check that the applet can find the file, which seems to be ok.
However, it's not reading from the file.
Te file is a simple text file - fields are seperated by a comma and a space.
Any ideas?
Please help as this is quite urgent.
Prototype Code is below
public class cinema extends Applet implements ActionListener, ItemListener{
private List ActionList;
private int listIndex;
TextArea t = new TextArea(5, 30);
private Button gobutton, writebutton, login, logout;
private PrintWriter suggestfile;
TextField Userid, password, enterField;
private int count, checkuser;
private BufferedReader firstn;
File myFile = new File("e:\\Ian\\Unistuff\\2nd Year\\se2\\cinema2\\src\\cinema2\\member.txt");
//Construct the applet
public cinema() {
enterField = new TextField("Please enter user ID and Password");
enterField.setEditable(false);
add(enterField);
Userid = new TextField(3);
add(Userid);
password = new TextField(10);
password.setEchoChar('*');
add(password);
//Initialize the applet
public void init() {
BorderLayout borderLayout1 = new BorderLayout();
//some code ommitted
t.setEditable(false);
add(t);
gobutton = new Button("Go!");
add(gobutton);
gobutton.addActionListener(this);
public void actionPerformed(ActionEvent event) {
if (event.getSource() == gobutton) {
try {
firstn = new BufferedReader( new FileReader(myFile));
catch (IOException e) {
t.setText("Member database missing - please contact Chairperson");
return;
try {
String line1;
boolean found = false;
while (( ( line1 = firstn.readLine() ) != null) && (! found))
{StringTokenizer token1 = new StringTokenizer (line1, " ,");
String user = token1.nextToken();
if (Userid.getText().equals(user))
{ found = true;
t.setText("Hello");
firstn.close();
catch (IOException e) {
System.err.println("Error Reading File " + myFile + ": " + e.toString());
Here's the text file:
Ian, Dodson, 001, rubbish
Joe, Bloggs, 002, medway
Bill, Smith, 003, unique
Guest, , Guest,
To test that it is working, it should just put a message in the Text Area, but nothing happens when you press the "go" button.1. Your applet will not work, because it is trying to
read file from local disk.
2. This task can be solved by simple CGI script
(which is much more common and universal thing than
java), so you do not need to use java if you want to
send 3 lines to a server.
3. See examples and read some books.1. Stated the obvious.
2. This is a java forum, not Perl.
3. Pathetic and patronizing.
Very helpful.
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