ALTER TABLE DROP
COLUMN
Drops a
column from a table.
SYNTAX
| table_name |
Name
of the table you are dropping the column from. |
| column_name |
Name
of the column you are dropping. |
DESCRIPTION
The ALTER
TABLE DROP COLUMN command modifies the definition of an existing table
and drops a column that was previously defined. To execute the ALTER TABLE
DROP COLUMN command on a table, you must be the table owner, have DBA
or SYSADM security privileges, or have the ALTER privilege for that table.
You can
use this command to drop a column from a table when it is no longer necessary.
You cannot drop a column if a primary or foreign key has been defined
on that column, unless you drop the primary or foreign key first. You
can drop a column if a view has been defined on that column, but the view
will be invalid and DBMaker will return an error when you try to use the
view. This command should be used with caution since the data in a column
cannot be recovered once you drop the column.
EXAMPLE
The following
command drops the BirthDate column from the Employees table.
ALTER TABLE Employees DROP (BirthDate)
|
The following
command drops the BirthDate and HireDate columns from the Employees table.
ALTER TABLE Employees DROP (BirthDate, HireDate)
|
RELATED COMMANDS
<
ALTER TABLE ADD COLUMN | Contents
| ALTER TABLE DROP FOREIGN KEY >
|
