Mysql 經常使用SQL語句集錦

如下是工做中經常使用的SQL語句 :

查詢時間，友好提示

• timestamp 日期類型

  $sql = "select date_format(create_time, '%Y-%m-%d') as day from table_name";

• int 時間戳類型

  $sql = "select from_unixtime(create_time, '%Y-%m-%d') as day from table_name";

一個sql 返回多個總數

$sql = "select count(*) all, " ;
$sql .= " count(case when status = 1 then status end) status_1_num, ";
$sql .= " count(case when status = 2 then status end) status_2_num ";
$sql .= " from table_name";

Update Join / Delete Join

$sql = "update table_name_1 ";
$sql .= " inner join table_name_2 on table_name_1.id = table_name_2.uid ";
$sql .= " inner join table_name_3 on table_name_3.id = table_name_1.tid ";
$sql .= " set *** = *** ";
$sql .= " where *** ";

//delete join 同上。

替換某字段的內容的語句

$sql = "update table_name set content = REPLACE(content, 'aaa', 'bbb') ";
$sql .= " where (content like '%aaa%')";

獲取表中某字段包含某字符串的數據

$sql = "SELECT * FROM `表名` WHERE LOCATE('關鍵字', 字段名) ";

獲取字段中的前4位

$sql = "SELECT SUBSTRING(字段名,1,4) FROM 表名 ";

查找表中多餘的重複記錄

• 單個字段

  $sql = "select * from 表名 where 字段名 in ";
  $sql .= "(select 字段名 from 表名 group by 字段名 having count(字段名) > 1 )";

• 多個字段

  $sql = "select * from 表名 別名 where (別名.字段1,別名.字段2) in ";
  $sql .= "(select 字段1,字段2 from 表名 group by 字段1,字段2 having count(*) > 1 )";

刪除表中多餘的重複記錄(留id最小)

• 單個字段

  $sql = "delete from 表名 where 字段名 in ";
  $sql .= "(select 字段名 from 表名 group by 字段名 having count(字段名) > 1) ";
  $sql .= "and 主鍵ID not in ";
  $sql .= "(select min(主鍵ID) from 表名 group by 字段名 having count(字段名 )>1) ";

• 多個字段

  $sql = "delete from 表名 別名 where (別名.字段1,別名.字段2) in ";
  $sql .= "(select 字段1,字段2 from 表名 group by 字段1,字段2 having count(*) > 1) ";
  $sql .= "and 主鍵ID not in ";
  $sql .= "(select min(主鍵ID) from 表名 group by 字段1,字段2 having count(*)>1) ";

Thanks ~

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