concat()用法

Posted 2020-11-02 白莲花の

  

SELECT school_code,`name`,phone from student WHERE login_name REGEXP \'ning$\'LIMIT 10;

            

 concat()

• SELECT CONCAT(school_code,`name`) from student WHERE login_name REGEXP \'ning$\' LIMIT 10;

           

• SELECT CONCAT(school_code,`name`,phone) from student WHERE login_name REGEXP \'ning$\' LIMIT 10;（有一个字段是null，concat的结果是null）

          

  CONCAT_WS()

• SELECT CONCAT_WS(\'-\',school_code,NAME,login_name,phone) from student WHERE login_name REGEXP \'ning$\' LIMIT 10;

           

•  SELECT `name`,MIN(id) FROM student GROUP BY `name` HAVING COUNT(id) >=2 LIMIT 10;

          

 

 GROUP_CONCAT()

• SELECT id,`name` from student WHERE `name`=\'刘媛媛\' LIMIT 10;

            

• SELECT NAME,GROUP_CONCAT(id) from student WHERE `name`=\'刘媛媛\' LIMIT 10;

           

•  SELECT NAME,GROUP_CONCAT(id) FROM student GROUP BY `name` HAVING COUNT(id) >=2 LIMIT 10;