Mysql 中有哪些常用的SQL語(yǔ)句

今天就跟大家聊聊有關(guān)Mysql 中有哪些常用的SQL語(yǔ)句，可能很多人都不太了解，為了讓大家更加了解，小編給大家總結(jié)了以下內(nèi)容，希望大家根據(jù)這篇文章可以有所收獲。

查詢(xún)時(shí)間，友好提示

• timestamp 日期類(lèi)型

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

• int 時(shí)間戳類(lèi)型

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

一個(gè)sql 返回多個(gè)總數(shù)

$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(nèi)容的語(yǔ)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(shù)據(jù)

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

查找表中多余的重復(fù)記錄

• 單個(gè)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(gè)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 )";

刪除表中多余的重復(fù)記錄(留id最小)

• 單個(gè)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(gè)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) ";

看完上述內(nèi)容，你們對(duì)Mysql 中有哪些常用的SQL語(yǔ)句有進(jìn)一步的了解嗎？如果還想了解更多知識(shí)或者相關(guān)內(nèi)容，請(qǐng)關(guān)注億速云行業(yè)資訊頻道，感謝大家的支持。