topic Re: difference between select single * and select upto 1 row in Application Development and Automation Discussions

difference between select single * and select upto 1 row

Former Member — Tue, 17 Apr 2007 12:53:03 GMT

what is the difference between select single * and select upto 1 row.

Re: difference between select single * and select upto 1 row

Former Member — Tue, 17 Apr 2007 12:56:01 GMT

With SELECT single gives it only one result with a fully qualified key. One... limits the number of values

Re: difference between select single * and select upto 1 row

Former Member — Tue, 17 Apr 2007 12:57:27 GMT

Hi,

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.

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.

reward if useful

regards,

Anji

Re: difference between select single * and select upto 1 row

Former Member — Tue, 17 Apr 2007 12:58:06 GMT

Hi,

select single * and select upto 1 row. will get the same data.

but performance wisw select single * is good.and u don't need to endselect for select single *

rgds,

bharat.

Re: difference between select single * and select upto 1 row

Former Member — Tue, 17 Apr 2007 13:12:34 GMT

hi josh,

select single

The result of the selection should be a single entry. If it is not possible to identify a unique entry, the system uses the first line of the selection. For e.g.

that is It fetches single record from the database, based on the condition you specified in the where clause.

DATA : ITAB TYPE ZREKHA_EMP.

SELECT SINGLE *

FROM ZREKHA_EMP

INTO ITAB

WHERE EMPNO = ‘00101’ AND

DEPTNO = ‘0010’.

WRITE : / ITAB-EMPNO, ITAB-EMPNAME .

select upto n rows

Fetches first record if the condition specified in the where clause is satisfied, otherwise it doesn't fetch any record

SELECT field

INTO w_field

FROM table

UP TO 1 ROWS.

ENDSELECT.

Re: difference between select single * and select upto 1 row

alex_m — Tue, 17 Apr 2007 13:42:16 GMT

If you have all key fields for selection then go for Select Single, if you dont have all the key in selection go for Up to 1 rows.