select single * and up to 1 rows

[Former Member]

Hi Experts,

What is the exact difference between select single *...and select up to 1 rows?

and which is faster in exicution?

Regards

[RichHeilman]

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

Regards,

Rich Heilman

[anversha_s]

Hi Ravi,

chk this.

ex code

***********

Report Z_Difference

Message-id 38

Line-Size 80

Line-Count 0

No Standard Page Heading.

Start-Of-Selection.

Data: w_Single type Posnr,

t_Rows type standard table of Posnr

initial size 0

with header line.

Select single Posnr

from zDifference

into w_Single.

Select Posnr

into table t_Rows

from zDifference

up to 1 rows

order by Posnr descending.

Write 😕 'Select single:', w_Single.

Skip 1.

Write 😕 'Up to 1 rows :'.

Loop at t_Rows.

Write t_Rows.

EndLoop.

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

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.

You can refer to the below link..

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

rgds

anver

if hlped pls mark points

[Former Member]

Hi,

Select single fetches only a single record based on the where conditon

select...upto 1 rows selects all the records satisfying the where condition but displays only one record

[Former Member]

select single is used for primary key fields

select up to 1 rows is used for non key fields.

and select single st. stops the search after finding corresponding value. but select up to 1 rows does the search for the entire table even after matching the criteira.

[Former Member]

Check

REgards,

Santosh

[Former Member]

Hi all,

Thanks.

[Former Member]

Hi,

Select single is faster.

With select up to i rows ...database hit high compare

to select single.

Performance point of view select single is the best.

Go to SE30--> Runtime analysis .....see tips & Tracks.

Thnaks & regards,

padmaja