Mysql 常用SQL语句集锦
1. 查询时间，友好提示1) timestamp 日期类型<br>
$sql = "select date_format(create_time, '%Y-%m-%d') as day from table_name";<br>
2) int 时间戳类型<br>
$sql = "select from_unixtime(create_time, '%Y-%m-%d') as day from table_name";2. 一个sql 返回多个总数$sql = "select count(*) all, " ;<br>
$sql .= " count(case when status = 1 then status end) status_1_num, " ; <br>
$sql .= " count(case when status = 2 then status end) status_2_num ";<br>
$sql .= " from table_name";3. Update Join / Delete Join$sql = "update table_name_1 ";<br>
$sql .= " inner join table_name_2 on table_name_1.id = table_name_2.uid ";<br>
$sql .= " inner join table_name_3 on table_name_3.id = table_name_1.tid ";<br>
$sql .= " set *** = *** ";<br>
$sql .= " where *** ";<br>
//delete join 同上。4. 替换某字段的内容的语句$sql = "update table_name set content = REPLACE(content, 'aaa', 'bbb') ";<br>
$sql .= " where (content like '%aaa%')";5. 获取表中某字段包含某字符串的数据$sql = "SELECT * FROM `表名` WHERE LOCATE('关键字', 字段名) ";6. 查找表中多余的重复记录1) 单个字段<br>
$sql = "select * from 表名 where 字段名 in ";<br>
$sql .= "(select 字段名 from 表名 group by 字段名 having count(字段名) > 1 )";<br>
2) 多个字段<br>
$sql = "select * from 表名 别名 where (别名.字段1,别名.字段2) in ";<br>
$sql .= "(select 字段1,字段2 from 表名 group by 字段1,字段2 having count(*) > 1 )";更多【干货分享】，请关注一位有情怀的工程师。
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