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Alter a table column from VARCHAR to NULL in MySQL
To alter, use the ALTER command with CHANGE as in the below syntax −
alter table yourTableName change yourColumnName yourColumnName datatype NULL DEFAULT NULL;
Let us first create a table −
mysql> create table DemoTable1356 -> ( -> FirstName varchar(30) -> ); Query OK, 0 rows affected (0.56 sec)
Let us implement the above syntax to alter a table column to NULL −
mysql> alter table DemoTable1356 change FirstName FirstName varchar(30) NULL DEFAULT NULL; Query OK, 0 rows affected (0.17 sec) Records: 0 Duplicates: 0 Warnings: 0
Insert some records in the table using insert command −
mysql> insert into DemoTable1356 values('Adam');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1356 values('John');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1356 values();
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable1356 values('Bob');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable1356 values(NULL);
Query OK, 1 row affected (0.24 sec)Display all records from the table using select statement −
mysql> select * from DemoTable1356;
This will produce the following output −
+-----------+ | FirstName | +-----------+ | Adam | | John | | NULL | | Bob | | NULL | +-----------+ 5 rows in set (0.00 sec)
Updated on: 05-Nov-2019
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