Is it better to use join?

hi
i want to select header details from LIKP and item details from LIPS. i have VBELN number with me. now there are two scenarios
in first one
i can use select single to get the header details
then chekc sy-subrc to make sure that document exists in the system then query LIPS to get the item details.
second case
use join between LIKP and LIPS join on VBELN.
what would be the best in terms of performance in case if u want to select only one item from LIPS?

Hi Sudhakar ,
Proceed with the INNER JOIN between tables LIKP and LIPS based on VBELN to fetch Header and Item details.
This will resolve your issue.

Similar Messages

How do i get data from a structure using join?

hi,
what is the actual use of a structure.?
my problem is :
KUAGV is an existing STRUCTURE. it has got one fields each which links to MARA, AND VBKD tables. i want to fetch all related information from KUAGV, mara, vbkd . which is the better way : using joins or views or anything else? how do i
get data from a structure using join?

structure temporarily holds any data passed to it dynamically throughout the runtime but doesnot store it permanently. so
a structure cannot be included in a join.so instead of incuding structure KUAGV's field in a join
search the transparent table in which same field are present and use it in join.
A structure if created in DDIC(Data Dictionary) is a global DATA STRUCTURE which is used to group related information, for example you would group all the details of your bank account into a structure BANK_ACCOUNT that contains fields like account_Id, account_holder_name etc.
If you create a structure in your program then it is local to your program. So you use this structure to create data holders of this DATA TYPE to hold data in your program.
Edited by: suja thomas on Feb 11, 2008 6:24 AM
Edited by: suja thomas on Feb 11, 2008 6:31 AM

How can we say if Join better than using Sub Queries ??

Hi all,
I am trying to understand the rationale behind "Is _Inner Join_ better than using _Sub Query_ ?" for this scenario ...
I have these tables --
Table1 { *t1_Col_1* (PrimaryKey), t1_Col_2, t1_Col_3, t1_Col_4 }
-- Number of rows = ~4Million , t1_Col_3 has say 60% entries non-zero -----> (Condition 4)
Table2 { *t2_Col_1* (PK), t2_Col_2, t2_Col_3 }
-- Number of rows = ~150Million, t2_Col_2 maps to t1_Col_1 -----> (Condition 1). This means for every distinct value of t1_Col_1 (its PK) we'll have multiple rows in Table2.
Table3 { *t3_Col_1* (PK), t3_Col_2, t3_Col_3 }
-- Number of rows = ~50K, t3_Col_1 maps to t1_Col_2 -----> (Condition 2)
Table4 { *t4_Col_1* (PK), t4_Col_2, t4_Col_3 }
-- Number of rows = ~1K, t4_Col_2 maps to t3_Col_2 -----> (Condition 3)
Now here are the 2 queries: -
Query using direct join --
SELECT t1_Col_1, t2_Col_1, t3_Col_1, t4_Col_2
FROM Table1, Table2, Table3, Table4
WHERE t1_Col_1=t2_Col_2 -- Condition 1
AND t1_Col_2=t3_Col_1 -- Condition 2
AND t3_Col_2=t4_Col_1 -- Condition 3
AND t1_Col_3 != 0
Query using SubQuery --
SELECT t1_Col_1, t2_Col_1, t3_Col_1, t4_Col_2
FROM Table2,
(SELECT t1_Col_1, t3_Col_1, t4_Col_2
FROM Table1,Table3, Table4
WHERE
AND t1_Col_2=t3_Col_1 -- Condition 2
AND t3_Col_2=t4_Col_1 -- Condition 3
AND t1_Col_3!= 0
WHERE t1_Col_1=t2_Col_2 -- Condition 1
Now the golden question is - How can I document with evidence that Type-1 is better than Type-2 or the other way ? I think the 3 things in comparison are: -
- Number of rows accessed (Type-1 better ?)
- Memory/Bytes used (Again Type-1 better ?)
- Cost ( ?? )
(PS - testing on both MySQL, Oracle10g)
Thanks,
A

So, is it right to conclude that Optimizer uses the optimal path and then processes the query resulting in nearly the same query execution time ?If the optimizer transforms two queries so that they end up the same, then they will run in the same time. Of course, sometimes it cannot do so because of the the way the data is defined (nulls are often a factor; constraints can help it) or the way the query is written, and sometimes it misses a possible optimization due to inaccurate statistics or other information not available to it, or limitations of the optimizer itself.
Is this the right place to ask for MySQL optimization ?Probably not.

For All Entries is NOT better than INNER JOIN in most cases

I quote from Siegfried Boes' excellent post here: Will writing an inner join be better or creating a view?
For all the FOR ALL ENTRIES lovers ... there is no proof for these reappearing recommendation.
There is nearly nobody who receives forum points, who recommends FOR ALL ENTRIES instead of Joins. What is the reason ???
It is easier to prove the opposite. A Join is a nested loop inside the database, a FOR ALL ENTRIES is partly outside of the database. FOR ALL ENTRIES works in blocks, joins on totals.
FOR ALL ENTRIES are not recommded on really large tables, because the chances are too high that
too many records are transferred.
People prefer FOR ALL ENTRIES, because JOINs are not so easy to understand. Joins can go wrong, but with a bit of understanding they can be fixed.
Some Joins are slow and can not be fixed, but then the FOR ALL ENTRIES would be extremely slow.
There are several kinds of views:
- projection views, i.e. only one table involved just fields reduced
- join views, several tables, joins conditions stored in dictionary
- materialized views, here the joined data are actually stored in the database. Storing and synchronisation has to be done manually.
Only the last one creates real overhead. It should be the exception.
Join Views and Joins are nearly identical. The view is better for reuse. The join is better in complicated, becuase if the access goes wrong, it can often be fixed by adding a hint. Hints can not be added to views.
Abraham Bukit points out:
If it is cluster table, (you can't use join). If it is buffered table, I would also say avoid join.
If they all are transaction table which are not buffered and are not cluster tables.
He further supports Siegfried's statement that FAE is easier to undestand than INNER JOINs.
Thomas Zloch says, regarding buffered tables:
At least think twice, maybe compare runtimes if in doubt.
So, unless someone has some EVIDENCE that FOR ALL ENTRIES is better, I don't think we want to see this discussed further.
Kind regards
Matt

To give food for thought here's an example I gave in a thread:
If you have a statement like
SELECT ... FOR ALL ENTRIES IN FAE_itab WHERE f = FAE_itab-f.
SAP sends it to the database depending how the parameter rsdb/prefer_union_all is set:
rsdb/prefer_union_all = 0 =>
SELECT ... WHERE f = FAE_itab[1]-f
          OR    f = FAE_itab[2]-f
          OR    f = FAE_itab[N]-f
You have some influence of the generated statement type: Instead of OR'ed fields an IN list can be used
if you have only a single coulmn N to compare:
rsdb/prefer_in_itab_opt parameter:
SELECT ... WHERE f IN (itab[1]-f, itab[2]-f, ..., itab[N]-f)
rsdb/prefer_union_all = 1 =>
SELECT ... WHERE f = FAE_itab[1]-f
UNION ALL SELECT ... WHERE f = FAE_itab[2]-f
UNION ALL SELECT ... WHERE f = FAE_itab[N]-f
see: Note 48230 - Parameters for the SELECT ... FOR ALL ENTRIES statement
As you can see for the 2nd parameter several statements are generated and combined with a UNION ALL,
the first setting generates statements with OR's (or uses IN if possible) for the entries in FAE_itab.
I give you a little example here (my parameters are set in a way that the OR's are translated to IN lists; i traced the execution in ST05)
Select myid into table t_tabcount from mydbtable
for all entries in t_table    " 484 entries
    where myid = t_table-myid .
ST05 trace:
|Transaction SEU_INT|Work process no 0|Proc.type DIA|Client 200|User |
|Duration |Obj. name |Op.    |Recs.|RC    |Statement|
| 640|mydbtable |PREPARE|   | 0|SELECT WHERE "myid" IN ( :A0 , :A1 , :A2 , :A3 , :A4 ) AND "myid" = :A5|
| 2|mydbtable |OPEN   |   | 0|SELECT WHERE "myid" IN ( 1 , 2 , 3 , 4 , 5 ) AND "myid" = 72 |
| 2.536|mydbtable |FETCH |    0| 1403|   |
| 3|mydbtable |REOPEN |   | 0|SELECT WHERE "myid" IN ( 6 , 7 , 8 , 9 , 10 ) AND "myid" = 72 |
| 118|mydbtable |FETCH | 0| |
| 2|mydbtable |REOPEN | | 0|SELECT WHERE "myid" IN ( 11 , 12 , 13 , 14 , 15 ) AND "myid" = 72     |
| 3|mydbtable |REOPEN | | 0|SELECT WHERE "myid" IN ( 475 , 476 , 477 , 478 , 479 ) AND "myid" = 72 |
| 94|mydbtable |FETCH | 0| 1403|   |
| 2|mydbtable |REOPEN |   | 0|SELECT WHERE "myid" IN ( 480 , 481 , 482 , 483 , 484 ) AND "myid" = 72 |
You see the IN list contained 5 entries each , wich made up about 97 statements for all 484 entries.
For every statment you have a single fetch operation wich means a separate access to the database.
If you would replace the FAE with a join you would only have one fetch to the database.
With the example above we can derive these observations:
1. From database point of view these settings kill performance when you access a big table and/or have a lot of entries or columns in your FAE_itab. Furthermore, you hide information what data you will access
at all and thus you block the database from creating a more efficient execution plan because it DOESN'T KNOW wich data you will select in the next step. I.e. it may be more efficient to scan the table in one shot instead of having many index accesses - but the database can make this decision only if it can examine ONE statement that has ALL the information of what data to retrieve.
2. A second impact is that with every statement execution you trigger the allocation of database resources
wich will contribute to the overhead described above.
Said that, FAE can never be a replacement for joining big tables (think of having a table with thousands of records in a FAE table )
Edited by: kishan P on Nov 2, 2010 2:16 PM - Format Fixed

Which is better to use Store Procedure or Views in Crystal Reports ?

Hi,
which one is more better to use Store Procedure or Views in Crystal Reports ?
Thanks.

It depeneds on the requirement. Well, but from performance point of view as u know that stored procedures are already compiled on DB side, they would be more efficient. Views are handled differently. Here CR has nothing to do with it.
But if the stored procedure u r using is having 2 Select statements, CR will only display the results from the first select statement. In that case you need to use Views as one can use more than one views in the report and join them.
Using a Generic view which is created by the DBA for a larger audience will result in performance issues meaning if a View "V" has 25 fields and View is based on 5 tables and ur report is using only 5 fields which are coming only from 2 tables inside the view,in this case u will end up in joining 3 more tables unnecessarily.
Hope this helps!

About SQL Query using joins

Hi,
I want to write a SQL statement using Joins. The base table "A" has about 100 fields and the join table "B" a few. I would like to fetch all fields from table "A" and a few from table "B".
Is there a way to write a query wherein I can use "Select * " for table "A" rather than writing all 100 field name in the query? Please keep in mind that I want to use a Join.
Thanks.

Hi Thomas,
but if there are some fields which are in both tables, SELECT * will be not sufficient. E.g. fields ERNAM, ERDAT, AENAM, AEDAT are such fields which can occur in more tables. In case that a target area will contain these fields, by * with addition INTO CORRESPONDING FIELDS OF, you are not able to specify from which table these values should be taken. In such case, it can be solved by specifying field list dynamically. If it is not that case SELECT * is sufficient. You should check intersection of common fields for tables you are joining. Thereafter you should decide if you can use SELECT *.
Maybe for better understanding, what exactly I am talking about, look at this example:
TYPES: BEGIN OF ts_data,
        ernam TYPE mara-ernam,
       END OF ts_data.
DATA: ls_data TYPE ts_data,
      ls_mara TYPE mara,
      ls_mchb TYPE mchb.
START-OF-SELECTION.
ls_mara-matnr = '1'.
ls_mchb-matnr = ls_mara-matnr.
ls_mara-ernam = 'A'.
ls_mchb-ernam = 'B'.
INSERT mara FROM ls_mara.
INSERT mchb FROM ls_mchb.
SELECT SINGLE * FROM mara INNER JOIN mchb ON mara~matnr = mchb~matnr INTO CORRESPONDING FIELDS OF ls_data.
ROLLBACK WORK.
You as a developer are not able to tell from which table common fields should be selected. But maybe this is really too specific case...
Regards,
Adrian

Query using JOIN

Hi,
my tables structure looks:
Column names:
rhead
bu
sub_bu
report_order
sub_bu_order
q1py
My query is:
select Rhead,bu,Sub_bu,report_order,sub_bu_order,q1py,case
          when sub_bu='ISS' then (select q1py from tsg a where a.sub_bu='ESS' and a.rhead=b.rhead)
          when sub_bu='TS' then (select q1py from tsg a where a.sub_bu='Services' and a.rhead=b.rhead)
          when sub_bu='SW' then (select q1py from tsg a where a.sub_bu='SW' and a.rhead=b.rhead)
          else NULL end as q1py_bu,
          case
          when sub_bu='ISS' then (select q1py from tsg a where a.sub_bu='TSG' and a.rhead=b.rhead)
          when sub_bu like 'R&D' and rhead in ('Region owned opex','% of revenue','Region opex','Region opex%') then
          (select q1py from tsg a where a.sub_bu like 'TSG' and a.rhead=b.rhead)
          else NULL end as q1py_tot from tsg b where report_order=1
Result:
rhead bu sub_bu report_order sub_bu_order q1py q1py_bu q1py_tot
orders ESS ISS 1 1 1162 1778.4 2953.9
here i am using the sub query to produce the result. I need to give the same result by using JOINS.
So any one help me, by using JOINS instead of SUB QUERY and produce the same result
Thanx in advance

Hi,
this is my query
select
Rhead,BU,Sub_bu,report_order,sub_bu_order,q1py,
case
          when sub_bu='ISS' then (select q1py from tsg a where a.sub_bu='ESS' and a.rhead=b.rhead)
          when sub_bu='TS' then (select q1py from tsg a where a.sub_bu='Services' and a.rhead=b.rhead)
          when sub_bu='SW' then (select q1py from tsg a where a.sub_bu='SW' and a.rhead=b.rhead)
          else NULL end as q1py_bu,
case
          when sub_bu='ISS' then (select q1py from tsg a where a.sub_bu='TSG' and a.rhead=b.rhead)
          when sub_bu like 'R&D' and rhead in ('Region owned opex','% of revenue','Region opex','Region opex%') then
          (select q1py from tsg a where a.sub_bu like 'TSG' and a.rhead=b.rhead)
          else NULL end as q1py_tot
last_update from tsg where @condition;
i will use the different conditions. they are
1.sub_bu<>bu and report_order<=8
2.report_order > 8 and report_order<11 and sub_bu not in (‘TSG’)
3.report_order > 10 and report_order <14
4.report_order > 13
i used the above query and getting some time.
so i am using the below query as suggested by forum earlier.
select
Rhead,BU,Sub_bu,report_order,sub_bu_order,q1py,
case
when sub_bu='ISS'
then max(case when sub_bu='ESS' then q1py end) over(partition by rhead)
when sub_bu='TS'
then max(case when sub_bu='Services' then q1py end) over(partition by rhead)
when sub_bu='SW'
then max(case when sub_bu='SW' then q1py end) over(partition by rhead)
end as q1py_bu,
case
when sub_bu='ISS'
then max (case when sub_bu='TSG' then q1py end) over (partition by rhead)
when sub_bu = 'R&D' and rhead in ('Region owned opex','% of revenue','Region opex','Region opex%')
then max(case when sub_bu = 'TSG' then q1py end) over (partition by rhead)
end as q1py_tot, last_update from tsg where @condition;
I am getting better result by this query.
but the problem is this query gives wrong output for first two conditions(1.sub_bu<>bu and report_order<=8
2.report_order > 8 and report_order<11 and sub_bu not in (‘TSG’). The value is not displayed for the virtual column q1py_bu and q1py_tot.
i am getting this warning message too
Warning: Null value is eliminated by an aggregate or other SET operation.
I am not able to find the solution. so plz do help in this..
other than this every thing is fine
thanks

2 Questions How to use join() and Which is best coding pratice.

Hi All,
I have 2 Question:
I have a MultipleThread class and when I try to use join method of thread class I get compile time error(so i commented it out).I also wanted to know is the best approch to write a threaded program.I also wanted to know about the best coding pratice for threadand also do I need to declare Instance variable thread and name(Is it possible to create multiple thread with out declaring instance variable thread and name , if yes which one is the better way 1> with instance variable 2> with out instance variable)

Sorry here is the code.
package javaProg.completeReferance;
public class MultipleThread implements Runnable
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     String name;
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          this.name=nam;
          thread = new Thread(this,name);
          thread.start();
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          catch (InterruptedException e)
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               //t2.join();
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                    System.out.println("Parent Thread "+i);
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               System.out.println(" "+e);
}

Using join and batch reading in the same query

Hi,
I wonder if it is possible to use "Joining" and "batch reading" in the same query.
For example I Have
A -> 1-1 B
A -> 1-1 B
B -> 1-M C
This is the case where I have two separate 1-1 relationships to the same class B from A. Toplink 10.0.3 can manage it nicely through joining.
Now, I would like to read a set of As (with its 2 Bs) and all Cs for each B.
It seems that the following configuration does not work:
A -> 1-1 B (use joining)
A -> 1-1 B (use joining)
B -> 1-M C (Batch read)
Any help would be greatly appreciated
Tony.

James,
Would you be so kind to look at the following code?
Am I formulating it correctly to achieve my desired behavior?
Trip.class -> 1-1 PickupStop
Trip.class -> 1-1 DropoffStop
PickupStop and DropoffStop extend Stop and use same table (STOP)
Stop -> 1-M StopEvents
I would like to fetch all Trips, with their Stops and all StopEvents in 2 queries:
1. Trip joined with Stop
2. Batchread StopEvents
Code:
ReadAllQuery raq = new ReadAllQuery(Trip.class);
Expression qexp1 = new ExpressionBuilder();
Expression qexp2 = new ExpressionBuilder();
raq.addJoinedAttribute("pickupStop");
raq.addJoinedAttribute("dropoffStop");
raq.addBatchReadAttribute(qexp1.get("pickupStop").get("vStopEvents"));
raq.addBatchReadAttribute(qexp2.get("dropoffStop").get("vStopEvents"));

My firefox beta 12 using Linux platform does not update to firefox RC1 via the "check for update" function. I know windows' beta version had this fixed, when would Linux get similar support ?

Current platform : Linux
Current firefox version : Firefox 4 beta 12
Issue : does not update to RC 1 using the check for update feature.
Background : previously downloaded beta 8 and then it automatically updated to beta 12 using update features but for RC1, it does not.
I know users under Windows platform had same problem but was resolved and they can now update via check for update feature.
Please implement for Linux users too.
Thanks !!

If you can't update then you can download and install the full Firefox 4 RC version.
* http://www.mozilla.com/firefox/all-beta.html

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WD RED models are designed for RAID and NAS and 7.2k instead of your more standard slower green 5400 rpm green models while still costing less than WD Blacks.
http://www.amazon.com/gp/product/B008JJLW4M/
How to clone your system:
http://macperformanceguide.com/Mac-HowToClone-backup.html
http://macperformanceguide.com/Mac-HowToClone.html
http://www.macupdate.com/app/mac/7032/carbon-copy-cloner
Using Cloning as a Backup Strategy
http://www.macupdate.com/app/mac/7032/carbon-copy-cloner
http://www.bombich.com/software/updates/ccc-3.5.html
Clone to internal, TimeMachine to NAS is one way to go at it.

Which one better to use - jsp:useBean or import statement

Hi,
I just want to know that which one is better to use jsp:useBean or import statement .
I can instantiate and call method of myclass -
1) by importing the class through import tag in jsp as <%@page import="myclass"%. or
2). by using <jsp:useBean tag....
i have these two option to do the same thing. i know that basically useBean is used to call setter and getter method of bean class and but it can be used to call a normal java file that have some logic .
so what should i used , which one is better and why?
useBean provides scope and object instance so no need to create object by new operator. and with import you have to create an instance .
but which tag should i use in my jsp?
i am confused???

ok, means i can use jsp:useBean tag for all my
classes that are not actually bean. so it will be
instantiated at run time and provide efficiency .No. Jsp:useBean is used for java bean components.
>
but when should i use import statement in my jsp and
it happen at translation time so will it create any
type of burden for my code if i import multiple
classes.For non-java beans, you need to import the classes, period.
It's not a burden, it's a necessity.

Which is better to use in a corprate enviornment for back up Windows 2008 Vs. Mozy

Which is better to use in a corprate enviornment for back up Windows 2008 Vs. Mozy

Hi,
Microsoft provide the built-in backup utility Windows Server Backup to backup Windows server 2008. For more detailed information, please refer to the articles below:
Windows Server Backup Step-by-Step Guide for Windows Server 2008
http://technet.microsoft.com/en-us/library/cc770266(v=ws.10).aspx
Save big bucks without risk: Get the most from Windows Server 2008 Backup Utility
http://www.techrepublic.com/blog/data-center/save-big-bucks-without-risk-get-the-most-from-windows-server-2008-backup-utility/
Please Note: Since the website is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
For Microsoft does not provide any third party software, you need to check with the third party software yourself.
Regards,
We
are trying to better understand customer views on social support experience, so your participation in this
interview project would be greatly appreciated if you have time.
Thanks for helping make community forums a great place.

Is it better to use join?

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