MySQL query to set values for NULL occurrence

Find NULL values using the IS NULL and update the new values using MySQL UPDATE and SET −

update yourTableName set yourColumnName=yourValue where yourColumnName IS NULL;

Let us first create a table −

mysql> create table DemoTable768 (    Clientid int NOT NULL AUTO_INCREMENT PRIMARY KEY,    ClientName varchar(100),    ClientAge int ); Query OK, 0 rows affected (0.47 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable768(ClientName,ClientAge) values('John',23); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable768(ClientName,ClientAge) values(NULL,26); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable768(ClientName,ClientAge) values('Carol',28); Query OK, 1 row affected (0.53 sec) mysql> insert into DemoTable768(ClientName,ClientAge) values(NULL,24); Query OK, 1 row affected (0.16 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable768;

This will produce the following output -

+----------+------------+-----------+ | Clientid | ClientName | ClientAge | +----------+------------+-----------+ |        1 | John       |        23 | |        2 | NULL       |        26 | |        3 | Carol      |        28 | |        4 | NULL       |        24 | +----------+------------+-----------+ 4 rows in set (0.00 sec)

Following is the query to set values for NULL occurrence −

mysql> update DemoTable768    set ClientName='Chris'     where ClientName IS NULL; Query OK, 2 rows affected (0.41 sec) Rows matched: 2 Changed: 2 Warnings: 0

Let us check the description of the view −

mysql> select *from DemoTable768;

This will produce the following output -

+----------+------------+-----------+ | Clientid | ClientName | ClientAge | +----------+------------+-----------+ |        1 | John       | 23 | |        2 | Chris      | 26 | |        3 | Carol      | 28 | |        4 | Chris      | 24 | +----------+------------+-----------+ 4 rows in set (0.00 sec)