Question

I want to union 3 different statements, the problem is that I am using a loop and if in my query:

WHILE some condition

BEGIN
 if(condition 1)
  begin
     select something
  end

 else if(condition 2)
  begin
     select something
  end


 else if(condition 3)
  begin
     select something
  end

END

The query is working fine but it returns more than 100 different select results (distinct tables). How can I union these select results into one table?

Answer 1

If you mean in TSQL, then you need a temporary table (#foo) or table variable (@bar). Then at each step:

INSERT {name} ({cols})
SELECT {cols}
{etc}

Then do a final

SELECT {cols}
FROM {name}

The choice between table-variable and temporary-table is subtle. I prefer table-variables; but for large data, or if you need an identity/index, a temporary-table may be more versatile. But if you aren’t inside a SPROC you must ensure you clean up your temp table.