DB2（找到光标）无效关键字“找到”

Question

I'm having a serious problem with DB2 Cursor. When I'm opening it I cant know is there any records in it or not?

And also I'm writing my stored procedure in IBM® Data Studio Version 4.1.0.0

Answer 1

You must run the FETCH statement to check, if there are records in the result set. But you can't do it since you return the result to a caller.

So, the 1-st solution would be to use, let's say, (Declared | Created) Global Temporary Table to INSERT SELECT into it with checking, if any rows were inserted (using GET DIAGNOSTICS statement), and then open either cursor1 on this (C|D)GTT, or cursor2.

The 2-nd solution would be to combine both select statements into a single one like below:

SELECT T.*
FROM
(
  SELECT 
    RANK() OVER (ORDER BY NUMBER) RN
  , T.*
  FROM
  (
    SELECT 1 AS NUMBER, T1.*
    FROM SYSIBM.SYSDUMMY1 T1
    --WHERE 1=0
      UNION ALL
    SELECT 2 AS NUMBER, T2.*
    FROM SYSIBM.SYSDUMMY1 T2
  ) T
) T
WHERE RN=1;

The idea is to UNION both result sets, rank them by their constant column value ( NUMBER in this case), and return the result subset with the smallest rank.