Question

我对mysql存储过程和变量有疑问;

表名：es_adwords 字段：id＃image_source＃image_link＃computer_id＃is_all_pc＃image_state #flag_size

我想创建应该搜索computer_id = {pc_number}和image_state = 0的存储过程。

如果不是，则存储过程应返回等于is_all_pc = 1。

DELIMITER $$
DROP PROCEDURE IF EXISTS `GetAdwordsBanner` $$
DELIMITER $$
CREATE PROCEDURE `GetAdwordsBanner`(IN compid INT)
BEGIN
SET @result_id := 0;

SELECT @result_id := id FROM es_adwords WHERE image_state = 1 AND computer_id = compid ORDER BY id DESC LIMIT 0,1;

IF (@result_id != 0) THEN
    SELECT image_source,image_link,banner_size FROM es_adwords WHERE image_state = 1 AND computer_id = compid ORDER BY id DESC LIMIT 0,1;
ELSE
    SELECT image_source,image_link,banner_size FROM es_adwords WHERE image_state = 1 AND is_all_pc = 1 ORDER BY id DESC LIMIT 0,1;
END IF;

END $$
DELIMITER ;

真诚的你......

Answer 1

你的逻辑有问题。我会把它重写为：

DELIMITER $$
CREATE PROCEDURE `GetAdwordsBanner`(IN compid INT)
BEGIN
-- use a local variable instead of a user variable
DECLARE result_count INT;
-- count how many rows are matching
SELECT COUNT(*) INTO result_id FROM es_adwords WHERE image_state = 1 AND computer_id = compid;

-- if there are matches    
IF result_count > 0 THEN
    -- return the first matching row
    SELECT image_source,image_link,banner_size FROM es_adwords WHERE image_state = 1 AND computer_id = compid ORDER BY id DESC LIMIT 0,1;
ELSE
    -- return the default one
    SELECT image_source,image_link,banner_size FROM es_adwords WHERE image_state = 1 AND is_all_pc = 1 ORDER BY id DESC LIMIT 0,1;
END IF;

END $$
DELIMITER ;

这应该有用。

Mysql设置变量存储过程

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