如何使用 MySQL COALESCE() 函数在列中的 NULL 位置插入值？

为了理解它，我们使用表“Employee”中的数据，其中 ID = 5 和 6 的 Salary=NULL，如下 -

mysql> Select * from Employee; +----+--------+--------+ | ID | Name   | Salary | +----+--------+--------+ | 1  | Gaurav | 50000  | | 2  | Rahul  | 20000  | | 3  | Advik  | 25000  | | 4  | Aarav  | 65000  | | 5  | Ram    | NULL   | | 6  | Mohan  | NULL   | +----+--------+--------+ 6 rows in set (0.00 sec)登录后复制

mysql> Update Employee set Salary = COALESCE(Salary,20000) where Id = 5; Query OK, 1 row affected (0.09 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> Update Employee set Salary = COALESCE(Salary,30000) where Id = 6; Query OK, 1 row affected (0.06 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> Select * from Employee; +----+--------+--------+ | ID | Name   | Salary | +----+--------+--------+ | 1  | Gaurav | 50000  | | 2  | Rahul  | 20000  | | 3  | Advik  | 25000  | | 4  | Aarav  | 65000  | | 5  | Ram    | 20000  | | 6  | Mohan  | 30000  | +----+--------+--------+ 6 rows in set (0.00 sec)登录后复制