ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name
alter_specification [, alter_specification] ...
alter_specification:
table_options
| ADD [COLUMN] col_name column_definition
[FIRST | AFTER col_name ]
| ADD [COLUMN] (col_name column_definition,...)
| ADD {INDEX|KEY} [index_name]
[index_type] (index_col_name,...) [index_option] ...
....
以上命令可以在MySQL命令行中鍵入help alter或help alter table獲得
很顯然從語法上看，要麼 ADD [COLUMN] col_name column_definition [FIRST | AFTER col_name ]
要麼，ADD [COLUMN] (col_name column_definition,...)
加多個列的時候，無法 [FIRST | AFTER col_name ]
