Question

对于我的项目，我有一个奇怪的要求!!

我有三个表，如ATab，BTab和CTab，如下所示

CREATE TABLE IF NOT EXISTS `ATab` (
`id` int(8) unsigned NOT NULL AUTO_INCREMENT,
`oid` int(8) unsigned NOT NULL,
`type` int(1) unsigned NOT NULL ,
`parent` int(8) unsigned NOT NULL ,
`title` varchar(128) CHARACTER SET utf8 NOT NULL DEFAULT '' ,
`tagname` varchar(16) CHARACTER SET utf8 NOT NULL DEFAULT '',
`uid` int(8) NOT NULL COMMENT 'uid',
`name` varchar(64) CHARACTER SET utf8 DEFAULT NULL ,
`ctime` int(8) NOT NULL ,
`utime` int(11) DEFAULT NULL ,
`lnk` varchar(64) DEFAULT NULL ,
 PRIMARY KEY (`id`),
 KEY `re` (`oid`),
 KEY `re_type` (`type`),
 KEY `rg_parent` (`parent`)
 ) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

CREATE TABLE IF NOT EXISTS `BTab` (
`pid` int(8) unsigned NOT NULL AUTO_INCREMENT,
`ptype` int(1) DEFAULT NULL ,
`pname` varchar(128) CHARACTER SET utf8 DEFAULT NULL,
 PRIMARY KEY (`pid`),
 KEY `ptype` (`ptype`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

CREATE TABLE IF NOT EXISTS `CTab` (
`cid` int(11) unsigned NOT NULL AUTO_INCREMENT,
`id` int(11) DEFAULT NULL,
`mvl` text CHARACTER SET utf8,
 PRIMARY KEY (`cid`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

示例条目：

INSERT INTO `ATab` (`id`, `oid`, `type`, `parent`, `title`, `tagname`, `uid`, `name`, `ctime`, `utime`, `lnk`) VALUES
(1, 1, 1, 1, 'child1', 'test', 1, 'john', 1383740369, 1383740369, '1'),
(2, 1, 2, 1, 'child2', 'test', 1, 'john', 1383740379, 1383740379, '1'),
(3, 2, 1, 2, 'child3', 'sample', 2, 'jose', 1383740389, 1383740399, '2'),
(4, 2, 2, 2, 'child4', 'sample', 2, 'jose', 1383740479, 1383740479, '2');

INSERT INTO `BTab` (`pid`, `ptype`, `pname`) VALUES
(1, 1, 'parent1'),
(2, 2, 'parent2');


INSERT INTO `CTab` (`cid`, `id`, `mvl`) VALUES
(1, 1, '{\r\n    "test": "test json data "\r\n}'),
(2, 2, '{\r\n    "sample": "sample json data"\r\n}');

BTab包含父条目。 ATab包含BTab中条目的子条目。父母会有多个孩子。 CTab包含与ATab相关的数据（CTab.id = ATab.id）。 CTab中没有条目用于ATab中的所有条目（所以我使用了LEFT OUTER JOIN）。

我的SELECT查询： -

SELECT CONCAT(  "{\"items\":[", CONVERT( GROUP_CONCAT(  "{\"t", 
TYPE ,  "\":{\"id\":", ATab.id,  ",\"oid\":", oid,  ",\"ty\":", 
TYPE ,  ",\"p\":", parent,  ", \"rtnm\":\"", tagname,  "\",\"tl\":\"", title,  "\", \"nm\":\"", name,  "\", \"ct\":", ctime,  ", \"ut\":", utime,  ", \"u\":", uid,  " , \"mvl\":", IFNULL( CTab.mvl,  "{}" ) ,  ",\"lnk\":\"", IFNULL( lnk,  "0" ) ,  "\"}}" ) 
USING utf8 ) ,  "]}" ) AS jsn
FROM ATab
JOIN BTab
LEFT OUTER JOIN CTab ON CTab.id = ATab.id
WHERE oid =1
AND ATab.parent = BTab.pid
AND ATab.parent
IN ( 1 ) 
GROUP BY ATab.parent
ORDER BY utime DESC 
LIMIT 0 , 500

输出将是JSON为

{
    "items": [
        {
            "t1": {
                "id": 1,
                "oid": 1,
                "ty": 1,
                "p": 1,
                "rtnm": "test",
                "tl": "child1",
                "nm": "john",
                "ct": 1383740369,
                "ut": 1383740369,
                "u": 1,
                "mvl": {
                    "test": "test json data "
                },
                "lnk": "1"
            }
        },
        {
            "t2": {
                "id": 2,
                "oid": 1,
                "ty": 2,
                "p": 1,
                "rtnm": "test",
                "tl": "child2",
                "nm": "john",
                "ct": 1383740379,
                "ut": 1383740379,
                "u": 1,
                "mvl": {
                    "sample": "sample json data"
                },
                "lnk": "1"
            }
        }
    ]
}

我需要根据utime（ORDER BY utime DESC）对结果进行排序。但输出没有排序。我认为问题与我使用的CONCAT声明有关（我不确定）。我无法改变JSON结构。我希望数据库处理排序。查询工作正常。

任何帮助都将受到高度赞赏......

修改

~~对不起伙计..我尝试创建一个sqlfiddle网址。但我没有得到sqlfiddle网站..可能是网络问题:(~~

Sqlfiddle网址：http://sqlfiddle.com/#!2/3564f/1

Answer 1

在评论部分中提及sled - 将ORDER BY移到GROUP_CONCAT内。因此：

SELECT CONCAT(  "{\"items\":[", CONVERT( GROUP_CONCAT(  "{\"t", 
TYPE ,  "\":{\"id\":", ATab.id,  ",\"oid\":", oid,  ",\"ty\":", 
TYPE ,  ",\"p\":", parent,  ", \"rtnm\":\"", tagname,  "\",\"tl\":\"", title,  "\", \"nm\":\"", name,  "\", \"ct\":", ctime,  ", \"ut\":", utime,  ", \"u\":", uid,  " , \"mvl\":", IFNULL( CTab.mvl,  "{}" ) ,  ",\"lnk\":\"", IFNULL( lnk,  "0" ) ,  "\"}}" ORDER BY utime DESC ) 
USING utf8 ) ,  "]}" ) AS jsn
FROM ATab
JOIN BTab
LEFT OUTER JOIN CTab ON CTab.id = ATab.id
WHERE oid =1
AND ATab.parent = BTab.pid
AND ATab.parent
IN ( 1 ) 
GROUP BY ATab.parent
LIMIT 0 , 500;

ORDER BY不使用MySQL中的CONCAT语句

1 个答案: