topic Re: Select Single in Application Development and Automation Discussions

Select Single

Former Member — Thu, 28 Jun 2007 07:20:13 GMT

Hi ,

Can any body tell the exact difference between Select Single & Select Upto X Rows & Which is better performance wise

Re: Select Single

Former Member — Thu, 28 Jun 2007 07:22:08 GMT

According to SAP Performance course the SELECT UP TO 1 ROWS is faster than SELECT SINGLE because you are not using all the primary key fields.

select single is a construct designed to read database records with primary key. In the absence of the primary key, it might end up doing a sequential search, whereas the select up to 1 rows may assume that there is no primary key supplied and will try to find most suitable index.

The best way to find out is through sql trace or runtime analysis.

Use "select up to 1 rows" only if you are sure that all the records returned will have the same value for the field(s) you are interested in. If not, you will be reading only the first record which matches the criteria, but may be the second or the third record has the value you are looking for.

The System test result showed that the variant Single * takes less time than Up to 1 rows as there is an additional level for COUNT STOP KEY for SELECT ENDSELECT UP TO 1 ROWS.

The 'SELECT SINGLE' statement selects the first row in the database that it finds that fulfils the 'WHERE' clause If this results in multiple records then only the first one will be returned and therefore may not be unique.

Mainly: to read data from

The 'SELECT .... UP TO 1 ROWS' statement is subtly different. The database selects all of the relevant records that are defined by the WHERE clause, applies any aggregate, ordering or grouping functions to them and then returns the first record of the result set.

Re: Select Single

Former Member — Thu, 28 Jun 2007 07:22:46 GMT

hi thuyavan,

<b>Select Single and Select UpTo One Rows</b>

According to SAP Performance course the SELECT UP TO 1 ROWS is faster than SELECT SINGLE because you are not using all the primary key fields.

The best way to find out is through sql trace or runtime analysis.

The System test result showed that the variant Single * takes less time than Up to 1 rows as there is an additional level for COUNT STOP KEY for SELECT ENDSELECT UP TO 1 ROWS.

USE: to read data from

USE: to check if entries exist.

http://www.sap-basis-abap.com/abap/difference-between-select-single-and-up-to-1-row.htm

http://www.sap-img.com/abap/difference-between-select-single-and-select-upto-one-rows.htm

Regards...

Arun.

Reward points if useful.

Re: Select Single

Former Member — Thu, 28 Jun 2007 07:23:16 GMT

Hi Thuyavan ,

Select single will select the first available row which satisifes the given condition , where as select up to X rows will select all the rows which satisfy the said condition but return only X rows as output.

You can see the exact diffrence when you add the addition like ORDER By in the select upto X rows .

In this case the result retured by select single and select upto 1 rows can be diffrent.

Hope this helps.

Regards

Arun

Re: Select Single

Former Member — Thu, 28 Jun 2007 07:23:19 GMT

Difference Between Select Single and Select UpTo One Rows

According to SAP Performance course the SELECT UP TO 1 ROWS is faster than SELECT SINGLE because you are not using all the primary key fields.

The best way to find out is through sql trace or runtime analysis.

The System test result showed that the variant Single * takes less time than Up to 1 rows as there is an additional level for COUNT STOP KEY for SELECT ENDSELECT UP TO 1 ROWS.

Mainly: to read data from

Mainly: to check if entries exist.

Reward points for useful Answers

Regards

Anji

Re: Select Single

Former Member — Thu, 28 Jun 2007 07:25:23 GMT

Hi,

Performancewise select single is faster it will take first row without sort and groupin gof database

Select upto one row will take some time more but it will give the exact output with sorting and grouping of database table.

Regards,

nandha

Reward if it helsp

Re: Select Single

Former Member — Thu, 28 Jun 2007 07:28:20 GMT

HI.

Setect UP TO 1ROWS is best performance ,it is best when you dont know about key fildes.

if you know key fildes SINGLE it is best.

SELECT UP TO 1 ROWS is faster than SELECT SINGLE because you are not using all the primary key fields.

Reward all helpfull answers.

Regards.

Jay