适用场景,如表tab_a 有三个字段,
如果field1非空则按升序排列,
如果field1是空再排field2,
如果 field2非空升序排列,
如果field2是空再排field3,
如果field3非空则升序排列,
如果field3是空。。。。。。。。
例子1 排序boolean类型
CREATE TABLE `tab_b` (
`field` varchar(255) default NULL,
`id` int(11) default NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `tab_b` VALUES ('1', 'ture');
INSERT INTO `tab_b` VALUES ('2', 'ture');
INSERT INTO `tab_b` VALUES ('3', 'false');
INSERT INTO `tab_b` VALUES ('4', 'false');
SELECT * from TAB_B ORDER BY field='true' desc
![](https://img-blog.csdn.net/20150116165028281?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvY2hhbmdsaWFuZ3ds/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center)
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注意:ORDER by 后接的字段如果是boolean属性,则false比ture ‘大’!!!!!
########################################################
DROP TABLE IF EXISTS `tab_a`;
CREATE TABLE `tab_a` (
`id` int(11) NOT NULL,
`field3` int(11) default NULL,
`field2` int(11) default NULL,
`field1` int(11) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `tab_a` VALUES ('1', '1', '1', '1');
INSERT INTO `tab_a` VALUES ('2', '2', '2', '2');
INSERT INTO `tab_a` VALUES ('3', '3', '3', null);
INSERT INTO `tab_a` VALUES ('4', '4', null, null);
INSERT INTO `tab_a` VALUES ('5', '5', '5', null);
INSERT INTO `tab_a` VALUES ('6', null, null, null);
INSERT INTO `tab_a` VALUES ('7', null, null, null);
INSERT INTO `tab_a` VALUES ('8', '8', null, null);
SELECT * FROM TAB_A ORDER BY
field1='' desc , field1 asc,
field2='' desc , field2 asc,
field3='' desc ,field3 asc
![](https://img-blog.csdn.net/20150116165209800?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvY2hhbmdsaWFuZ3ds/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center)
此处field1='' 可以看成boolean排序 desc 排序,field1=''为真的排在下面(因为看上面"注意"),否则排在上面(即field1!='');
而后面的field1 asc相当于排序field1!=''数据,依次排序field2,field3..........
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