Can I change a column from NOT NULL to NULL without dropping it?

Need to alter a table to allow nulls on a column -- but cant drop the column...can I do this? Was trying something like:

ALTER TABLE myTable MODIFY myColumn NULL;

B开发者_如何学Pythonut to no avail....

ALTER TABLE myTable ALTER COLUMN myColumn {DataType} NULL

where {DataType} is the current data type of that column (For example int or varchar(10))

Sure you can.

ALTER TABLE myTable ALTER COLUMN myColumn int NULL

Just substitute int for whatever datatype your column is.

The syntax is very based on database service

SQL Server / MS Access:

ALTER TABLE table_name
ALTER COLUMN column_name datatype NULL;

My SQL / Oracle (prior version 10G):

ALTER TABLE table_name
MODIFY COLUMN column_name datatype NULL;

Oracle 10G and later:

ALTER TABLE table_name
MODIFY column_name datatype NULL;

if you want to set a default value then:

ALTER TABLE table_name
ALTER COLUMN column_name datatype DEFAULT default_value;

For MYSQL

ALTER TABLE myTable MODIFY myColumn {DataType} NULL