Alter Column
The ALTER COLUMN command is used to change the data type of a column in a table.
The following SQL changes the data type of the column named "BirthDate" in the "Employees" table to type year:
Example
ALTER TABLE Employees
ALTER COLUMN BirthDate
year;Drop Column
The DROP COLUMN command is used to delete a column in an existing table.
The following SQL deletes the "ContactName" column from the "Customers" table:
Example
ALTER TABLE Customers
DROP COLUMN ContactName;