Is their a difference between primary key and unique key with not null valu

What is the difference in having a column as primary key and having unique key with not null for the column.
vinodh

SBH wrote:
For quick review, below is the link
http://www.dba-oracle.com/data_warehouse/clustered_index.htm
You appear to have stumbled on a site that is a mine of disinformation about Oracle.
>
It would be helpful, if you explain it too..thnx !!
The site is wrong and makes up its own terminology as it goes along.
If the value for clustering factor approaches the number of blocks in the base table, then the index is said to be clustered. http://www.oracle.com/pls/db112/search?remark=quick_search&word=clustered+index
There is no create clustered index in Oracle.
- Clustering factor affects the efficiency of an index.
- There can be clustered tables that you can create indexes on.
- An Index Organized table is a similar concept to the Microsoft SQL Server clustered index, but it isn't the same thing at all.

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Difference between PRIMARY KEY and UNIQUE KEY with NOT NULL

What is the difference between PRIMARY KEY and UNIQUE KEY with NOT NULL constraint?
Message was edited by:
Nilesh Hole

Answer for the master!!!
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:8743855576462
Thanks,
Karthick

Difference between primary eindex and secondary index?

hi experts
pls answer me
difference between primary eindex and secondary index?
rewads apply.
thanks.
naresh.

hi,
check this link.
http://help.sap.com/saphelp_47x200/helpdata/en/cf/21eb2d446011d189700000e8322d00/frameset.htm
A difference is made between Primary & Secondary indexes to a table. the primary index consists of the key fields of the table and a pointer to the non-keys-fields of the table. The Primary index is generated automatically when a table is created and is created in the datebase as the same times as the table. It is also possible to define further indexes to a table in the ABAP/4 dictionary, which are then referred to as Secondary indexes.
Always it is not mandatory that an index should have all the key fields of a table. To see the index of a table
goto SE11->specify table name->click on the indexes... button on the application toolbar.
Based on your requirement you can you any of those index fields in the where clause of your query. Always its a better practice to use the index fields in the order specified. While selecting the records from a table it is always better to select the fields in the same order as specified in the table.

Diff b/w primary key and unique key?

what is the diff b/w primary key and unique key?

Hi,
With respect to functionality both are same.
But in ABAP we only have Primary key for the Database tables declared in the Data Dictionary.
Unique is generally is the term used with declaring key's for internal tables.
Both primary and Unique keys can identify one record of a table.
Regards,
Sesh

Difference between Primary Key and Unique Key with NOT NULL constraint

As both can be referred to another table.
Apart from the difference that Primary Key can be only 1 and Unique keys can be multiple,
is there any difference?
Like in terms of type of Index?

PARAG_C wrote:
As both can be referred to another table.
Apart from the difference that Primary Key can be only 1 and Unique keys can be multiple,
is there any difference?
Like in terms of type of Index?Technically there is almost no difference. Logically the two are often used for slightly different concepts.
The PK (and with it the index) is often an ID column filled by a seqeunce. This key can then be refenced by foreign key constraints on other tables. it is very useful to have this as a meaningless technical construct. Because then the chance that such a ID needs to be changed is extremly slim.
The UK (and with it the index) is often one or several columns that represent the logical key for the entity. Foreign key constriants should not point to this. THe chance that this attribute will be changed at some point in time is way higher then for a meaningless number (ID).

Difference between Dimension Id and Dimension Key

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It says while building the BMM, don't drag the dimension Id columns from physical layer to logical layer as the BI Server takes care of the join for you but make sure you drag across the dimension key columns as you will need these later on to create your logical table keys.
Can someone enlighten me on what is the difference between a dimension id and dimension key (may be with an example).
Thanks.

Besides the theory says that a fact table can reference any level of a dimension, I couldn't do it with OWB. I don't know if there is a specific way to do that, but I only could assign a dimension detail level to a fact table.
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B) Setting up a MacsOSX server as Windows standalone server and joining the Active Directory using Directory Access;
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====================
We have a Windows 2003 A.D. running, all users are set up in the A.D.
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For Windows clients things aren't the same.
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Hi all,
Can anyone explain the difference between:
A) Setting up a MacOSX server as Windows domain member server using Server Manager;
B) Setting up a MacsOSX server as Windows standalone server and joining the Active Directory using Directory Access;
My setup:
====================
We have a Windows 2003 A.D. running, all users are set up in the A.D.
Also we have two MacOSX servers, which provide file services (both AFP and SMB/CIFS) for Mac and Windows clients, while using the A.D. for user authentication.
One of the MacOSX servers is configured as a domain member server, the other is configured as Windows standalone server. The latter is bound to the A.D. using Directory Access.
Following the Apple manuals one should think that the first setup (domain member) is the best.
As for Open Directory: both servers are running as Standalone.
How my setup behaves
====================
Official Apple guidelines are to set up the Mac server as domain member. Reality is another thing though.
For AFP both servers perform equal: users are authenticated against the A.D. and get access to their shares. File/Folder permissions are as expected.
For Windows clients things aren't the same.
The server setup as Windows Domain member acts strange. Windows clients don't have single signon experience.
Every file/folder's owner shared on this server is <<unknown>> to the client. Also, when a Windows user creates a file/folder the owner is <<unknown>>.
Sometimes the Samba server just stops authentication. A relaunch of the Samba service fixes this.
The server setup as a standalone server performs as expected. Windows clients have single signon experience, there are no issues with file/folder owner. Also authentication never stops.
Several kinds of Mac Mac OS X (10.4.9)

Differences between primary types and wrapes

Hi,
I am developing an two applications that change information over RMI, i can use primitive types, like long, boolean, int or wrapes of primary types like Long, Boolean, Integer
Beacuse both types are serializable, but i dont nkow what type must i use, somebody can explain me what is the best from the point of view of the performance and serialization????
thanks

The primitives, usually, unless you have a reason to use a wrapper.I would have said "...unless you absolutely have to." Autoboxing encourages the illusion that primitives and wrapper objects are interchangeable, and that's a dangerous illusion. Consider this example: import java.util.*;
public class Test
public static void main(String... args) throws Exception
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    int a = 1;
    Integer b = 2;
    int c = 300;
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    System.out.printf("%3d == %3d: %b%n", b, intList.get(1),
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2 ==   2: true
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My question is in the subject. Perhaps "differences" is not the good word. The positive and negative points ?
Imagine you have to write a connection pool, sure you gonna choose a singleton but why ?
Thank you very much.

A class is a class. Java doesn't have (and I wish it
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Wat is the exact differences between clustered table and pooled table

hi,
can you tell me ravi...wat is the exact differences between clustered table and pooled table
with regards//
anilreddyg

Hi Anil Reddy
Pooled Tables, Table Pools, Cluster Tables, and Table Clusters
These types of tables are not transparent in the sense that they are not legible or manageable directly using the underlying database system tools. They are managed from within the R/3 environment from the ABAP dictionary and also at runtime when they are loaded into application memory.Pool and cluster tables are logical tables. Physically, these logical tables are arranged as records of transparent tables. The pool and cluster tables are grouped together in other tables, which are of the transparent type. The tables that group together pool tables are known as table pools, or just pools; similarly, table clusters, or just
clusters, are the tables which group cluster tables.Not all operations that can be performed over transparent tables can be executed over pool or cluster tables.
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program parameters, documentation, and so on. Transaction and application data should be stored in transparent tables.
Table Pools
From the point of view of the underlying DBMS as from the point of view of the ABAP dictionary, a table pool is a transparent table containing a group of pooled tables which, when created, were assigned to this table pool.
Field Type Description
TABNAME CHAR(10) Table name
VARKEY CHAR(n) Maximum key length n =< 110
DATALN INT2(5) Length of the VARDATA record returned
VARDATA RAW(m) Maximum length of the data varies according to DBMS
Table Clusters
Similarly to pooled tables, cluster tables are logical tables which, when created, are assigned to a table cluster. Therefore, a table cluster, or just cluster, groups together several tables of type clusters.Several logical rows from different cluster tables are brought together in a single physical record. The records
from the cluster tables assigned to a cluster are thus stored in a single common table in the database.A cluster contains a transparent cluster key which must be located at the start of the key of all logical cluster tables to be included in the cluster. As well, a cluster contains a long field (VARDATA), which contains the
data of the cluster tables for this key. If the data does not fit into a field, continuation records are created.
Field Type Description
CLKEY1 CHAR(*) First key fields
CLKEY2 CHAR(*) Second key field
CLKEYN CHAR(*) nth key field
PAGENO INT2(5) Number of the next page
TIMESTMP CHAR(14) Time stamp
PAGELG INT2(5) Length of the VARDATA record returned
VARDATA RAW(*) Maximum length of the data section; varies according to database system
Working with Tables
The dictionary includes many functions for working with tables. There are five basic operations you can perform on tables: display, create, delete, modify, copy. Please do not confuse displaying a table with displaying the table entries (table contents). In order to display a table, it must previously exist; otherwise the system will display an error message in the status bar. For the following example, the table TABNA is used. To display this table, from the main dictionary screen, enter the table name in the Object name
input field with the radio button selected next to Tables. Then, click on the Display button at the bottom of the screen, or press the F7 function key, or, alternatively,
select Dictionary object Display from the menu.
In this screen, you can see table information such as
¨ Table type, shown next to the name of the object. In the example, it is a transparent table.
¨ Short text description.
¨ Name of the user who made the last change, and the date of the change.
¨ Master language.
¨ Table status. On the screen, you can see this table is saved and active.
¨ Development class. For information on development classes, refer to Chap. 6.
Delivery class, which sets the maintenance group for the table. It controls how tables will behave during client copy procedures, upgrades, and so forth.¨
Tab. Maint. Allowed flag, which indicates whether you can generate a screen for maintaining table entries.
¨Then, on the lower part of the screen, you can see the table fields with all associated characteristics such as:
¨ Field name.
¨ Key indicator. When set, this field is the primary key, or part of it.
¨ Data element.
¨ Basic data type.
¨ Length.
¨ Check table.
¨ Short text, describing the field.
Additional information about the table can be displayed by selecting the corresponding functions from the menu or directly from the application toolbar, such as keys, indexes, or technical settings
Standard table:
The key access to a standard table uses a sequential search. The time required for an access is linearly dependent on the number of entries in the internal table.
You should usually access a standard table with index operations.
Sorted table:
The table is always stored internally sorted by its key. Key access to a sorted table can therefore use a binary search. If the key is not unique, the entry with the lowest index is accessed. The time required for an access is logarithmically dependent on the number of entries in the internal table.
Index accesses to sorted tables are also allowed. You should usually access a sorted table using its key.
Hash table:
The table is internally managed with a hash procedure. All the entries must have a unique key. The time required for a key access is constant, that is it does not depend on the number of entries in the internal table.
You cannot access a hash table with an index. Accesses must use generic key operations (SORT, LOOP, etc.).
Index table:
The table can be a standard table or a sorted table.
Index access is allowed to such an index table. Index tables can be used to define the type of generic parameters of a FORM (subroutine) or a function module.
Just have a look at these links:
http://help.sap.com/saphelp_nw04/helpdata/en/90/8d7304b1af11d194f600a0c929b3c3/frameset.htm
http://help.sap.com/saphelp_nw04/helpdata/en/74/83015785d811d295a800a0c929b3c3/frameset.htm
Regards
Sreeni

Is their a difference between primary key and unique key with not null valu

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