diff between select single and upto

[Former Member]

Hi,

What is the differnce between

Select single * from vbak into table itab.

and

Select * from vbak into table itab upto 1 row.

thanks

[RaymondGiuseppi]

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.

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 or lack of, applies any aggregate, ordering or grouping functions to them and then returns the first record of the resultant result set.

Look for detail at <a href="http://www.sap-basis-abap.com/abap/difference-between-select-single-and-up-to-1-row.htm">Difference between select single and up to 1 row</a>

Regards

[Former Member]

Hi,

Check out this link.

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

This is the excerpt from the same link:

******************************************************************************

******************************************************************************

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.

Mainly: to check if entries exist.

******************************************************************************

******************************************************************************

Regards,

RS

[aris_hidalgo]

Hi Anil,

What others have said is correct. I will give a simple example to help you further.

*this is assuming the date given below is the earliest date...

DATA: gv_vbeln TYPE vbak-vbeln,

gv_erdat TYPE vbak-erdat.

SELECT SINGLE vbeln erdat

FROM vbak

INTO (gv_vbeln, gv_erdat)

WHERE erdat = '12/01/2006'.

SELECT vbeln erdat

FROM vbak UP TO 1 ROWS

INTO (gv_vbeln, gv_erdat)

ORDER BY erdat ASCENDING.

ENDSELECT.

*In the example, the select single gets the first record that satisfies the WHERE clause unlike in the UP TO 1 ROWS where it sorts the database records by the earliest date and gets its VBELN.

Hope this helps...

P.S. Please award points if it helps...

[Former Member]

hi..

there is no major difference between the select single and single upto 1 rows option..

The processing is similar...

the main difference...

In select single the complete set of primary key has to be specified in the where clause.

whereas in select ..upto one row only the most prominent primary key will have to be specified in the where clause.

[Former Member]

Hi

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 <b>'SELECT SINGLE'</b> 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.

<b>Mainly: to read data from</b>

The <b>'SELECT .... UP TO 1 ROWS'</b> 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.

<b>Mainly: to check if entries exist.</b>

Reward if helpful.