MySQL update column to NULL for blank values
For this, you can use IF() along with UPDATE command. Let us first create a table −
mysql> create table DemoTable1601
-> (
-> FirstName varchar(20) ,
-> LastName varchar(20)
-> );
Query OK, 0 rows affected (0.53 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable1601 values('John','Doe');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1601 values('Adam','');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable1601 values('David','Miller');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable1601 values('Chris','');
Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −
mysql> select * from DemoTable1601;
This will produce the following output −
+-----------+----------+
| FirstName | LastName |
+-----------+----------+
| John | Doe |
| Adam | |
| David | Miller |
| Chris | |
+-----------+----------+
4 rows in set (0.00 sec)
Following is the query to update column to null or its value −
mysql> update DemoTable1601 set LastName=if(LastName='',NULL,LastName);
Query OK, 2 rows affected (0.22 sec)
Rows matched: 4 Changed: 2 Warnings: 0
Let us check the table records once again −
mysql> select * from DemoTable1601;
This will produce the following output −
+-----------+----------+
| FirstName | LastName |
+-----------+----------+
| John | Doe |
| Adam | NULL |
| David | Miller |
| Chris | NULL |
+-----------+----------+
4 rows in set (0.00 sec)
Published on 16-Dec-2019 12:05:14
