Re: Datatype change of a Column

Have you tried as below :

ALTER TABLE Table

ALTER (Column Data_Type DEFAULT Default_Value,

Column Data_Type NULL);

Also below one :

ALTER TABLE

   You can change the definition of an existing column.

   For columns without a default value, you can specify one.

   For columns with a default value, you can change the existing value.

   The new (or first time) defined default value only affects newly inserted rows.

   For columns that do not allow NULL values so far, NULL values can be allowed.

ALTER TABLE Official

ALTER (Overtime INTEGER DEFAULT 7,

Salary VARCHAR(3) DEFAULT 'A01',

Name VARCHAR(20) NULL);