Question

I’m trying to come up with a simple example of a while loop using Microsoft SQL Server.
Here I’m looping through all the tables that begin with the word temp.

Declare @Object_ID int,@Name varchar(50)
set @Object_ID = 0
while exists (
    select * from 
    sys.tables
    where type = 'u' 
    and object_ID > @Object_ID 
    and Name like 'Temp%' 
) BEGIN
    select top 1 @Object_ID=Object_ID,@Name=Name
    from sys.tables
    where type = 'u' 
    and object_ID > @Object_ID 
    and Name like 'Temp%' 
    order by Object_ID
    exec('Select ''' + @Name + ''' as TableName,count(*) AS Counter from ' + @Name)
END

My problem is: now that I’ve looped through the tables, how do I use the information I’ve gathered with my exec command?
In other words, can I stored the table that is returned from the exec command into a variable?

Answer 1

Here is how I do this kind of task these days:

DECLARE
  @LoopId     int
 ,@Command    varchar(500)

DECLARE @List TABLE
 (
   TableName  sysname  not null
  ,LoopId     int      not null  identity(1,1)
 )

DECLARE @Results TABLE
 (
   TableName  sysname  not null
  ,Counter    int      not null
 )

--  Load with items you wish to review
INSERT @List (TableName)
 select name
  from sys.tables
  where Name like 'Temp%'
  order by Name desc

SET @LoopId = @@rowcount

--  Go through list and process each item
WHILE @LoopId > 0
 BEGIN
    SELECT @Command = 'SELECT ''' + TableName + ''' as TableName, count(*) as Counter from ' + TableName
     from @List
     where LoopId = @LoopId

    --  Load results in temp table
    INSERT @Results (TableName, Counter)
     execute (@Command)

    SET @LoopId = @LoopId - 1
 END

SELECT * from @Results