Question

I have a cursor that gets data and fetches it into @data_table. Then in the while loop I want to pass that @data_table into another cursor (as the table name) to run some more processing. I keep getting a declare @data_table error. How do I fix this?

DECLARE @var_name varchar(50)
DECLARE @data_table varchar(50)
DECLARE @data_value varchar(50)

DECLARE curDiscreteVars CURSOR LOCAL

FOR SELECT DISTINCT v.var_name, v.data_table 
    FROM dbo.vars v
    GROUP BY v.var_name, v.data_table

-- Loop through cursor, translating variable values as needed, and generate counts for each val_code for a variable
OPEN curDiscreteVars
FETCH NEXT FROM curDiscreteVars 
    INTO @var_name, @data_table

WHILE @@FETCH_STATUS  = 0
BEGIN
    --loop through all possible data values

    DECLARE curValues CURSOR LOCAL

    FOR SELECT DISTINCT @var_name  
        FROM @data_table

    OPEN curValues
    FETCH NEXT FROM curValues 
        INTO @data_value

    WHILE @@FETCH_STATUS  = 0
    BEGIN
        print @var_name



        FETCH NEXT FROM curValues 
        INTO @data_value
    END

    CLOSE curValues
    DEALLOCATE curValues

    FETCH NEXT FROM curDiscreteVars 
    INTO @var_name, @data_table
END

CLOSE curDiscreteVars
DEALLOCATE curDiscreteVars

Answer 1

I’m not sure I understand what you’re talking about doing, but variables cannot be used as table names. Or, really anything that’s not a field name. You’ll need to use dynamic SQL. That is, assign your SQL string to a variable, an then run EXEC() command.

For example:

 DECLARE @sqlcmd varchar(max)
 DECLARE @table_name sysname

 DECLARE cur_tables FOR
 SELECT name FROM sys.tables

 OPEN cur_tables
 FETCH NEXT FROM cur_tables INTO @table_name

 WHILE @@FETCH_STATUS = 0 BEGIN
 SET @sqlcmd = 'SELECT TOP 10 * FROM ' + QUOTENAME(@table_name)
 EXEC ( @sqlcmd )
 FETCH NEXT from cur_tables INTO @table_name
 END

 CLOSE cur_tables
 DEALLOCATE cur_tables

Alternately, if what you mean is that you need a location to store the data that is like a table, then create a temporary tabled for it.