MySQL query to update only a single field in place of NULL

For this, you can use COALESCE(). Let us first create a table −

mysql> create table DemoTable1805      (      Name1 varchar(20),      Name2 varchar(20)      ); Query OK, 0 rows affected (0.00 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1805 values('Chris',NULL); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1805 values('David','Mike'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1805 values(NULL,'Mike'); Query OK, 1 row affected (0.00 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1805;

This will produce the following output −

+-------+-------+ | Name1 | Name2 | +-------+-------+ | Chris | NULL  | | David | Mike  | | NULL  | Mike  | +-------+-------+ 3 rows in set (0.00 sec

Here is the query to update only one field −

mysql> update DemoTable1805      set Name1 = coalesce(Name1,Name2); Query OK, 1 row affected (0.00 sec) Rows matched: 3  Changed: 1 Warnings: 0

Let us check the table records once again −

mysql> select * from DemoTable1805;

This will produce the following output −

+-------+-------+ | Name1 | Name2 | +-------+-------+ | Chris | NULL  | | David | Mike  | | Mike  | Mike  | +-------+-------+ 3 rows in set (0.00 sec)