如何使用mysql在SubQuery结果中设置默认值

Question

如何使用mysql

在SubQuery结果中设置默认 VALUE

SELECT      
    p.`id`, p.`name`, p.`class_name`, cpd.`status_team`,
    cpd.`home`, cpd.`guest`, cpd.`mvp`, cpd.`oscar`,
    cpd.`wam`, cpd.`status`, cpd.`added_date`,
    (SELECT result FROM result_cards WHERE `id` = cpd.`result`) AS DEFAULT(`result`)
FROM `cron_players_data` cpd
INNER JOIN `players` p ON cpd.`player_id` = p.id
WHERE cpd.`added_date` = '2012-03-29' AND cpd.team_id = '15'

当我删除此 DEFAULT（）时，Query将正常执行。实际上我想默认结果值为0或者帮助肯定是值得赞赏的

Answer 1

解决方案IFNULL

SELECT      
p.`id`,p.`name`,p.`class_name`,cpd.`status_team`,cpd.`home`,cpd.`guest`,cpd.`mvp`,
cpd.`oscar`,cpd.`wam`,cpd.`status`,cpd.`added_date` ,
IFNULL((SELECT result FROM result_cards WHERE `id` = cpd.`result`),0) AS `result` 
FROM `cron_players_data` cpd INNER JOIN `players` p ON cpd.`player_id` = p.id
WHERE cpd.`added_date` = '2012-03-29' AND cpd.team_id = '15' 

Answer 2

您应该将子查询移动到连接。但是我无法理解你在尝试用DEFAULT（）做什么。您需要解释您想要实现的目标。

SELECT      
    p.`id`, p.`name`, p.`class_name`, cpd.`status_team`,
    cpd.`home`, cpd.`guest`, cpd.`mvp`, cpd.`oscar`,
    cpd.`wam`, cpd.`status`, cpd.`added_date`,
    IFNULL(rc.`result`, 0) AS `result`
FROM `cron_players_data` cpd
INNER JOIN `players` p
    ON cpd.`player_id` = p.id
LEFT JOIN result_cards rc
    ON cpd.`result` = rc.id
WHERE cpd.`added_date` = '2012-03-29'
AND cpd.team_id = '15'