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sqlsql-serverloopst-sqlsyntax
Macho
Macho

Reputation: 3607

Syntax of for-loop in SQL Server

What is the syntax of a for loop in TSQL?

Upvotes: 348

Views: 1006591

Answers (10)

Frobozz
Frobozz

Reputation: 233

Old thread but still coming up and I thought I would offer a "FOREACH" solution for those that need one.

DECLARE @myValue nvarchar(45);
DECLARE myCursor CURSOR FOR
SELECT [x] 
FROM (Values ('Value1'),('Value2'),('Value3'),('Value4')) 
as MyTable(x);
OPEN myCursor;
FETCH NEXT FROM myCursor INTO @myValue;
While (@@FETCH_STATUS = 0)
BEGIN
    PRINT @myValue
    FETCH NEXT FROM myCursor INTO @myValue;
END
CLOSE myCursor;     
DEALLOCATE myCursor;

I should state for the record that recursion is frowned upon in the SQL world. And for good reason - it can be very detrimental to performance. Still, for maintenance/offline/bulk/ad-hoc/testing/etc operations, I use this method a lot.

Upvotes: 6

Dan Cundy
Dan Cundy

Reputation: 2849

Extra Info

Just to add as no-one has posted an answer that includes how to actually iterate over a dataset inside a loop. You can use the keywords OFFSET FETCH.

Usage

DECLARE @i INT = 0;
SELECT @count=  Count(*) FROM {TABLE}

WHILE @i <= @count
BEGIN
       
    SELECT * FROM {TABLE}
    ORDER BY {COLUMN}
    OFFSET @i ROWS   
    FETCH NEXT 1 ROWS ONLY  

    SET @i = @i + 1;

END

Upvotes: 80

Mahesh Mitikiri
Mahesh Mitikiri

Reputation: 126

Try it, learn it: 

DECLARE @r INT = 5
DECLARE @i INT = 0
DECLARE @F varchar(max) = ''
WHILE @i < @r
BEGIN

    DECLARE @j INT = 0
    DECLARE @o varchar(max) = ''
    WHILE @j < @r - @i - 1
    BEGIN
        SET @o = @o + ' '
        SET @j += 1
    END

    DECLARE @k INT = 0
    WHILE @k < @i + 1
    BEGIN
        SET @o = @o + ' *'  -- '*'
        SET @k += 1
    END
    SET @i += 1
    SET @F = @F + @o + CHAR(13)
END
PRINT @F

With date:

DECLARE @d DATE = '2019-11-01'
WHILE @d < GETDATE()
BEGIN
    PRINT @d
    SET @d = DATEADD(DAY,1,@d)
END
PRINT 'n'
PRINT @d

Upvotes: 1

Sameer
Sameer

Reputation: 381

While Loop example in T-SQL which list current month's beginning to end date.

DECLARE @Today DATE= GETDATE() ,
@StartOfMonth DATE ,
@EndOfMonth DATE;

DECLARE @DateList TABLE ( DateLabel VARCHAR(10) );
SET @EndOfMonth = EOMONTH(GETDATE());
SET @StartOfMonth = DATEFROMPARTS(YEAR(@Today), MONTH(@Today), 1);

WHILE @StartOfMonth <= @EndOfMonth
BEGIN
    INSERT  INTO @DateList
    VALUES  ( @StartOfMonth );
    SET @StartOfMonth = DATEADD(DAY, 1, @StartOfMonth);
END;

SELECT  DateLabel
FROM    @DateList;

Upvotes: 0

Somnath Muluk
Somnath Muluk

Reputation: 57656

For loop is not officially supported yet by SQL server. Already there is answer on achieving FOR Loop's different ways. I am detailing answer on ways to achieve different types of loops in SQL server.

FOR Loop

DECLARE @cnt INT = 0;

WHILE @cnt < 10
BEGIN
   PRINT 'Inside FOR LOOP';
   SET @cnt = @cnt + 1;
END;

PRINT 'Done FOR LOOP';

If you know, you need to complete first iteration of loop anyway, then you can try DO..WHILE or REPEAT..UNTIL version of SQL server.

DO..WHILE Loop

DECLARE @X INT=1;

WAY:  --> Here the  DO statement

  PRINT @X;

  SET @X += 1;

IF @X<=10 GOTO WAY;

REPEAT..UNTIL Loop

DECLARE @X INT = 1;

WAY:  -- Here the REPEAT statement

  PRINT @X;

  SET @X += 1;

IFNOT(@X > 10) GOTO WAY;

Reference

Upvotes: 7

Amit
Amit

Reputation: 22076

T-SQL doesn't have a FOR loop, it has a WHILE loop
WHILE (Transact-SQL)

WHILE Boolean_expression
BEGIN

END

Upvotes: 253

i00
i00

Reputation: 77

How about this:

BEGIN
   Do Something
END
GO 10

... of course you could put an incremental counter inside it if you need to count.

Upvotes: 6

TcKs
TcKs

Reputation: 26632

There is no for-loop, only the while-loop:

DECLARE @i int = 0

WHILE @i < 20
BEGIN
    SET @i = @i + 1
    /* do some work */
END

Upvotes: 480

Ragul
Ragul

Reputation: 512

Simple answer is NO !!.

There is no FOR in SQL, But you can use WHILE or GOTO to achieve the way how the FOR will work.

WHILE :

DECLARE @a INT = 10

WHILE @a <= 20
BEGIN
    PRINT @a
    SET @a = @a + 1
END

GOTO :

DECLARE @a INT = 10
a:
PRINT @a
SET @a = @a + 1
IF @a < = 20
BEGIN
    GOTO a
END

I always prefer WHILE over GOTO statement.

Upvotes: 6

kashmir
kashmir

Reputation: 323

DECLARE @intFlag INT
SET @intFlag = 1
WHILE (@intFlag <=5) 
BEGIN
    PRINT @intFlag
    SET @intFlag = @intFlag + 1
END
GO

Upvotes: 29

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