DELETE FIRST 1000 ROWS

Question

DELETE FIRST 1000 ROWS

shashianireddy

SSC Eights!

Points: 914
More actions
March 29, 2014 at 2:21 am

#289833

I HAVE TABLE LIKE BELOW 3000 ROWS
NAME ADDRESS IDNO EMPCODE
SVR HYD 123456 9876
SGH HSD 98765 987654
.
.
.
.
I WANT DELETE FIRST 1000 ROWS IN SQL TABLE ............................
PLZ WRITE QUARIE ..........

Viewing 9 posts - 1 through 8 (of 8 total)

You must be logged in to reply to this topic. Login to reply

Lynn Pettis SSC Guru Points: 442467 More actions · Answer 1

shashianireddy (3/29/2014)
I HAVE TABLE LIKE BELOW 3000 ROWS
NAME ADDRESS IDNO EMPCODE
SVR HYD 123456 9876
SGH HSD 98765 987654
.
.
.
.
I WANT DELETE FIRST 1000 ROWS IN SQL TABLE ............................
PLZ WRITE QUARIE ..........

In SQL Server there really is no concept of first 1000 rows. So first question, how are you going to determine what are the first 1000 rows? By what column are you going to order the data and are you ordering it in ascending or descending order?

Here is a start:

DELETE TOP (1000) FROM MyTable ORDER BY yourOrderingColumn

gstarsaini Ten Centuries Points: 1010 More actions · Answer 2

You can use row number () to create ids for all the rows and then based on any column order you can delete 1000 rows:

DELETE FROM

(SELECT ROW_NUMBER()

OVER (ORDER BY Empcode) AS Row,

Name, Address, Idno

FROM Table_name) AS tablename

WHERE Row<=1000

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 3

Lynn Pettis (3/29/2014)
DELETE TOP (1000) FROM MyTable ORDER BY yourOrderingColumn

Msg 156, Level 15, State 1, Line 1

Incorrect syntax near the keyword 'ORDER'.

Amusingly enough, while updates and deletes can take a TOP, they can't have an ORDER BY clause.

To do a delete of the first x rows, ordered by something, this is what's needed:

DELETE FROM MyTable WHERE UniqueColumn IN (SELECT TOP(n) UniqueColumn FROM MyTable ORDER BY ColumnWhichDeterminesOrder)

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Lynn Pettis SSC Guru Points: 442467 More actions · Answer 4

GilaMonster (3/31/2014)
Lynn Pettis (3/29/2014)
DELETE TOP (1000) FROM MyTable ORDER BY yourOrderingColumn
Msg 156, Level 15, State 1, Line 1
Incorrect syntax near the keyword 'ORDER'.
Amusingly enough, while updates and deletes can take a TOP, they can't have an ORDER BY clause.
To do a delete of the first x rows, ordered by something, this is what's needed:
DELETE FROM MyTable WHERE UniqueColumn IN (SELECT TOP(n) UniqueColumn FROM MyTable ORDER BY ColumnWhichDeterminesOrder)

Thanks, don't know what I was thinking. Must be these 7 x 12+ hour days, not always thinking straight toward the end of the day.

Eirikur Eiriksson SSC Guru Points: 182882 More actions · Answer 5

This can be done using sub-query

Using TOP

DECLARE @BATCH_SIZE INT = 10;

DELETE X

FROM (

SELECT TOP (@BATCH_SIZE) [COLUMN]

FROM [TABLE_NAME] M

ORDER BY [COLUMN] DESC

) AS X

Using OFFSET-FETCH (2012)

DECLARE @BATCH_SIZE INT = 10;

DELETE X

FROM (

SELECT [COLUMN]

FROM [TABLE_NAME] M

ORDER BY [COLUMN] DESC

OFFSET 0 ROWS

FETCH FIRST (@BATCH_SIZE) ROWS ONLY

) AS X

Jeff Moden SSC Guru Points: 1003857 More actions · Answer 6

While some of the methods posted are ok, there's still the fundamental problem...

shashianireddy (3/29/2014)
I WANT DELETE FIRST 1000 ROWS IN SQL TABLE ............................

... of not knowing what the first 1000 rows should be.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Eirikur Eiriksson SSC Guru Points: 182882 More actions · Answer 7

Jeff Moden (3/31/2014)
While some of the methods posted are ok, there's still the fundamental problem...
shashianireddy (3/29/2014)
I WANT DELETE FIRST 1000 ROWS IN SQL TABLE ............................
... of not knowing what the first 1000 rows should be.

ooops :blush: (thundering voice: read the whole question....;-)

Ed Wagner SSC Guru Points: 287024 More actions · Answer 8

Once you determine what determines the first rows, I like using this approach:

WITH cte AS (

SELECT TOP 1000

FROM TableName

ORDER BY EntryDate ASC)

DELETE FROM cte;

This gives the added benefit of being able to replace the DELETE with a SELECT so you can see the rows that are going to be deleted before you actually delete them. However, the fundamental question of the order remains. Since the ONLY way to guarantee the order is by using an ORDER BY clause, don't skip this step.

Tally Tables - Performance Personified
String Splitting with True Performance
Best practices on how to ask questions