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Set value only for NULL values in a MySQL table
Use IFNULL to check for NULL values and set a value using the SET command. Let us first create a table −
mysql> create table DemoTable817(Value int); Query OK, 0 rows affected (0.53 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable817 values(10); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable817 values(null); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable817 values(20); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable817 values(null); Query OK, 1 row affected (0.11 sec)
Display all records from the table using select statement −
mysql> select *from DemoTable817;
This will produce the following output −
+-------+ | Value | +-------+ | 10 | | NULL | | 20 | | NULL | +-------+ 4 rows in set (0.00 sec)
Following is the query to set value only for NULL values −
mysql> update DemoTable817 set Value=IFNULL(Value,0); Query OK, 2 rows affected (0.17 sec) Rows matched: 4 Changed: 2 Warnings: 0
Let us check the table records once again −
mysql> select *from DemoTable817;
This will produce the following output −
+-------+ | Value | +-------+ | 10 | | 0 | | 20 | | 0 | +-------+ 4 rows in set (0.00 sec)
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