在SQL Server中创建动态联合查询

Question

I am trying to loop through my counter to create a dynamic sql query which should finally look like

I am trying to use this approach to get the final query but doesnt seems to work

declare @CurrentRow int 
set @CurrentRow =0;
declare @RowsToProcess int
declare @FinalHistoricalQuery varchar(5000)
WHILE @CurrentRow<3
 BEGIN       
   SET @FinalHistoricalQuery =' select 11'+convert(varchar(20),@CurrentRow) + ' union '
   SET @CurrentRow=@CurrentRow+1
 END

SET @FinalHistoricalQuery = left(@FinalHistoricalQuery,len(@FinalHistoricalQuery)-6)
exec (@FinalHistoricalQuery)

the final ouput that i am looking for is 110 111 112 but it comes as 112 Any suggestion would be helpfull

Answer 1

You missed to use the counter in dynamic query . Try something like this.

WHILE @CurrentRow<@RowsToProcess
 BEGIN       
   SET @FinalHistoricalQuery +=' select id from table'+convert(varchar(20),@CurrentRow) + ' union '
   SET @CurrentRow=@CurrentRow+1
 END

SET @FinalHistoricalQuery = left(@FinalHistoricalQuery,len(@FinalHistoricalQuery)-6)
exec (@FinalHistoricalQuery)