ALTER TABLE syntax - MySQL

ALTER [IGNORE] TABLE tbl_name alter_spec [, alter_spec ...]

 

alter_specification:

        ADD [COLUMN] create_definition [FIRST | AFTER column_name ]

  or    ADD INDEX [index_name] (index_col_name,...)

  or    ADD PRIMARY KEY (index_col_name,...)

  or    ADD UNIQUE [index_name] (index_col_name,...)

  or    ALTER [COLUMN] col_name {SET DEFAULT literal | DROP DEFAULT}

  or    CHANGE [COLUMN] old_col_name create_definition

  or    MODIFY [COLUMN] create_definition

  or    DROP [COLUMN] col_name

  or    DROP PRIMARY KEY

  or    DROP INDEX index_name

  or    RENAME [AS] new_tbl_name

  or    table_options

ALTER TABLE allows you to change the structure of an existing table. For example, you can add or delete columns, create or destroy indexes, change the type of existing columns, or rename columns or the table itself. You can also change the comment for the table and type of the table