Adds or drops (deletes) one or more columns (fields) from a table.


 ADD <column name> <data type> |
 DROP <column name>
 [, ADD <column name> <data type> |
 DROP <column name> ...]


Use ALTER TABLE to modify the structure of an existing table. ALTER TABLE with the ADD clause adds the column <column name> of the type <data type> to <table name>. Use the DROP clause to remove the existing column <column name> from <table>.


Data stored in a dropped column is lost without warning, regardless of the SET SAFETY setting.

Adding an autoincrement field will pack the table. All records marked for deletion will be lost.

Multiple columns may be added and/or dropped in a single ALTER TABLE command.

Use ALTER TABLE as a means of modifying the structure of a table without using the Table Designer.