mysql - 如何将查询结果存储到变量中？

Question

这是我的代码:

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，这些内部 IF 语句的条件几乎相同。那么我该如何改进呢？我的意思是如何将该查询的结果存储到变量中，然后使用该变量作为条件？

Answer 1

您现在可以在 if 语句中使用变量 condition

SET @condition := (SELECT 1 FROM users WHERE id = new.author_id AND IFNULL((active & b'1000000' > 0), 0) < 1);