我有一个查询(触发器),如下所示:
BEGIN
IF (new.edited_id IS NULL) THEN
IF (SELECT 1 FROM users WHERE id = new.author_id AND IFNULL((active & b'1000000' > 0), 0) < 1) THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = "you cannot ask anymore";
ELSEIF (SELECT 1 FROM users WHERE id = new.author_id AND IFNULL((active & b'10000000' > 0), 0) < 1) THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = "you cannot answer anymore";
END IF;
ELSE
IF (SELECT 1 FROM users WHERE id = new.author_id AND IFNULL((active & b'100000000' > 0), 0) < 1) THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = "you cannot edit anymore";
END IF;
END
如您所见,那些内部IF
语句的条件几乎相同。那我该如何改进呢?
我的意思是,如何将以下查询的结果存储到变量中:
SELECT active FROM users WHERE id = new.author_id;
然后将其用于以下条件:
IF (IFNULL((@variable & b'1000000' > 0), 0) < 1) THEN
IF (IFNULL((@variable & b'10000000' > 0), 0) < 1) THEN
IF (IFNULL((@variable & b'100000000' > 0), 0) < 1) THEN
我该如何处理?
答案 0 :(得分:1)
声明 local variable 并使用select语句的输出设置它。
DECLARE v_active bit(10);
SET v_active := (SELECT active FROM users WHERE id = new.author_id);