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Select Single & Select upto --> req when to use?

Former Member
0 Kudos

Hi Guys!

Can u pls tell me when to use select single * & when to use select upto 1 rows. with eg.

Thanks.

1 ACCEPTED SOLUTION

Former Member
0 Kudos

HI,

Select single is useful when we need to pick up unique record .

This is possible by giving all the primary key in the where condition .

Whereas up to 1 rows is used to pick one record as per the where condition ,

not necessarily to be unique .

Praveen.

10 REPLIES 10

Former Member
0 Kudos

Hi Rahul,

SELECT SINGLE * - If you are specifying all the KEY fields in your select query, then you can use this. You clearly know that this will return only one row, then you can use SELECT SINGLE *

SELECT UP TO 1 ROWS - If you want single row as output, but you are not specifying all the key fields, then you can use it.

Reward points if you find the answer informatory.

Best Regards,

Ram.

Former Member
0 Kudos

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.

<b>Reward points for useful Answers</b>

Regards

Anji

Former Member
0 Kudos

HI,

Select single is useful when we need to pick up unique record .

This is possible by giving all the primary key in the where condition .

Whereas up to 1 rows is used to pick one record as per the where condition ,

not necessarily to be unique .

Praveen.

Former Member
0 Kudos

hi,

1.SELECT SINGLE returns the first matching row for the given condition and it may not be unique, if there are more matching rows for the given condition.

2.SELECT ... UP TO 1 ROWS retrieves all the matching records and applies aggregation and ordering and returns the first record.

Inorder to check for the existence of a record then it is better to use SELECT

SINGLE than using SELECT ... UP TO 1 ROWS since it uses low memory and has better performance.

<b>reward points plz</b>

Former Member
0 Kudos

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.

Select Single

You need to mention all the key fields of the table.

No END SELECT required.

More performance compared to upto 1 row.

Where as UP to 1 row.

YOu can use if you do not have all the primiary key fields available.

END SELECT requeired.

Since all keys are not passing, possiblities of have other rows which satisfies the condition.

Select Statement with EndSelect is a loop, which in a single run retrieves a single Record. This Record has to be stored in a Work Area and then appended into an Internal Table.

Select Statements without EndSelect is not a loop and it retrieves the whole Record set matching the Criteria in a single shot and has to be Stored in an Internal Table Directly.

The most important thing to remember about the SELECT SINGLE is

There are several things to remember:

1) It retrieves only one row

2) It does not need an ENDSELECT statement

3) THE FULL KEY OF THE TABLE MUST BE INCLUDED IN

THE WHERE CLAUSE OF THE SELECT STATEMENT

to say in simple

SELECT SINGLE:

1. Select single is based on PRIMARY KEY

2. It will take the first record directly without searching of all relevant records.(Though you have lot of records for given condition)

SELECT UPTO 1 ROW :

It will check all records for given condition and take the first record .

It means in select single no searching, where as other searching.

Therefore, select single more efficient than UPTO 1 ROW.

Former Member
0 Kudos

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.

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.

Regards,

Priyanka.

Former Member
0 Kudos

Hi,

when you use select single

give all the primay key values in the where conditions...

it will give the record which is equal to your where conditions..

select upto 1 row will collect the one record from the database

in which the records are arranged defaultly in ascending order

so it will get the first record and depending on your where condition.

reward points if helpful,

thanks & regards,

venkatesh

former_member189059
Active Contributor
0 Kudos

HI Rahul

refer these links and threads.. you will get the proper reasons as well

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

https://www.sdn.sap.com/irj/sdn/wiki?path=/display/home/differencebetweenselectsingleandselectupto.&

Former Member
0 Kudos

hi

if u use select single --> u need to specify all the key fields then it fethces the single record.

if u use select upto one rows --> no need to specify key fields.... in output it shows single record only...

for better performance use select upto one row......

thanks,

maheedhar.t

Former Member
0 Kudos

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 '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.

Select Single

You need to mention all the key fields of the table.

No END SELECT required.

More performance compared to upto 1 row.

Where as UP to 1 row.

YOu can use if you do not have all the primiary key fields available.

END SELECT requeired.

Since all keys are not passing, possiblities of have other rows which satisfies the condition.

Select Statement with EndSelect is a loop, which in a single run retrieves a single Record. This Record has to be stored in a Work Area and then appended into an Internal Table.

Select Statements without EndSelect is not a loop and it retrieves the whole Record set matching the Criteria in a single shot and has to be Stored in an Internal Table Directly.

The most important thing to remember about the SELECT SINGLE is

There are several things to remember:

1) It retrieves only one row

2) It does not need an ENDSELECT statement

3) THE FULL KEY OF THE TABLE MUST BE INCLUDED IN

THE WHERE CLAUSE OF THE SELECT STATEMENT

<b>Reward points</b>

Regards