DB2 CASE/IF 条件控制语句

 IF语句格式(仅仅限于DB2过程、触发器、函数中使用) IF (条件)
  THEN 语句;
ELSEIF (条件)
  THEN 语句;
ELSEIF (条件)
  THEN 语句;
... ...
ELSE
  语句;
END IF;   例子：

BEGIN
	--取出最大ID   
SET NEW_ID=NULL;  
-- (SELECT TOP 1 my_id from TEMPVOUCHERNO ORDER BY my_id DESC)
SET NEW_ID=(SELECT my_id FROM "PIGGY".TEMPVOUCHERNO FETCH FIRST 1 ROWS ONLY);
--如果未取出来   
    IF NEW_ID IS NULL
			THEN SET NEW_ID='0000001';
			ELSE
			  BEGIN
					DECLARE NUM VARCHAR(7);
					--取出编号+1  CONVERT(VARCHAR,(CONVERT(INTEGER,RIGHT(NEW_ID,7))+1));
					--CAST((CAST(RIGHT(NEW_ID,7) as INTEGER)+1) as VARCHAR(7));
					--SET NUM=CONVERT(VARCHAR(7),(CONVERT(INTEGER,RIGHT(NEW_ID,7))+1));
		
					--SET NUM=REPLICATE('0',7-LEN(NUM))+NUM;
		
					SET NEW_ID=NUM; 
				END;
		END IF;
insert into "PIGGY".TEMPVOUCHERNO (my_id) values(NEW_ID);

END