我有两个表用户和查询。用户可以发布多个查询。
MySQL表架构: -
CREATE TABLE `users` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`email` varchar(100) NOT NULL,
`password` varchar(50) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
CREATE TABLE `queries` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`user_id` int(11) NOT NULL,
`address` text,
`city` varchar(100) NOT NULL,
`state` varchar(100) NOT NULL,
`zipcode` int(11) NOT NULL,
`created` datetime NOT NULL,
`modified` datetime NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
我想对查询从每个用户的查询表中获取5个查询应用限制。
我应该如何为此编写查询?
答案 0 :(得分:2)
试一试 -
SELECT x.*
FROM (SELECT t.user_id,t.id,
CASE
WHEN @category != t.user_id THEN @rownum := 1
ELSE @rownum := @rownum + 1
END AS rank,
@category := t.user_id AS var_category
FROM queries t
JOIN (SELECT @rownum := NULL, @category := '') r
ORDER BY t.user_id,t.id) X
WHERE x.rank<=5