Database Modification Table __ Database

Add field: Alter TALBE table name add field name type (width [, decimal places])

Modify field: ALTER TABLE name ALTER COLUMN field name type (width [, decimal places])

Rename field: ALTER TABLE name rename column field name to new field name

Delete field: ALTER TABLE Name drop column field name

For example, a table user (ID, username, password) adds a field sex:alter table user add sex varchar (2);

Modify field Sex:alter table users alter column sex varchar (4)

Rename field sex:exec sp_rename ' users.sex ', ' sexs '

                                    Delete field Sex:alter table users drop column sex