-- 获取A列中的总值 <--

DECLARE  cur_1  CURSOR  FOR  SELECT  SUM(A)  FROM  table_name;

OPEN  cur_1;

FETCH  cur_ 1  INTO  Sum_a;

CLOSE  cur_1; -- 获取B列中的总值 <--

DECLARE  cur_2  CURSOR  FOR  SELECT  SUM(B)  FROM  table_name;

OPEN  cur_2;

FETCH  cur_ 2  INTO  Sum_b;

CLOSE  cur_2; -- 获取C列中的总值 <--

DECLARE  cur_3  CURSOR  FOR  SELECT  SUM(C)  FROM  table_name;

OPEN  cur_3;

FETCH  cur_ 3  INTO  Sum_c;

CLOSE  cur_3; IF  Sum_a > Sum_b  THEN

SELECT  A FROM  table_name; ELSEIF  Sum_b > Sum_c THEN

SELECT  B  FROM  table_name; ELSE

SELECT  C  FROM  table_name;

END IF;;

END;// CALL ProcOut()//

2：

select case when A>B then case when A>C then A else C end else case when B>C then B else C end end as name from member 3: select (case when A>B then A else B end) as 'A’ , (case when B>C then B else C end) as  'B' from Person;