Can I Loop Through A Table Variable In T-SQL?


Answer :

Add an identity to your table variable, and do an easy loop from 1 to the @@ROWCOUNT of the INSERT-SELECT.

Try this:

DECLARE @RowsToProcess  int DECLARE @CurrentRow     int DECLARE @SelectCol1     int  DECLARE @table1 TABLE (RowID int not null primary key identity(1,1), col1 int )   INSERT into @table1 (col1) SELECT col1 FROM table2 SET @RowsToProcess=@@ROWCOUNT  SET @CurrentRow=0 WHILE @CurrentRow<@RowsToProcess BEGIN     SET @CurrentRow=@CurrentRow+1     SELECT          @SelectCol1=col1         FROM @table1         WHERE RowID=@CurrentRow      --do your thing here--  END 

DECLARE @table1 TABLE (     idx int identity(1,1),     col1 int )  DECLARE @counter int  SET @counter = 1  WHILE(@counter < SELECT MAX(idx) FROM @table1) BEGIN     DECLARE @colVar INT      SELECT @colVar = col1 FROM @table1 WHERE idx = @counter      -- Do your work here      SET @counter = @counter + 1 END

Believe it or not, this is actually more efficient and performant than using a cursor.


My two cents.. From KM.'s answer, if you want to drop one variable, you can do a countdown on @RowsToProcess instead of counting up.

DECLARE @RowsToProcess  int;  DECLARE @table1 TABLE (RowID int not null primary key identity(1,1), col1 int )   INSERT into @table1 (col1) SELECT col1 FROM table2 SET @RowsToProcess = @@ROWCOUNT   WHILE @RowsToProcess > 0 -- Countdown BEGIN     SELECT *         FROM @table1         WHERE RowID=@RowsToProcess      --do your thing here--      SET @RowsToProcess = @RowsToProcess - 1; -- Countdown END

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