添加/删除MySQL数据库表中的字段

添加字段的格式

ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name alter_specification [, alter_specification] ...alter_specification: table_option ... | ADD [COLUMN] col_name column_definition [FIRST | AFTER col_name ]

 

eg.

ALTER TABLE myTbl ADD COLUMN newItem VARCHAR(20) DEFAULT "0" AFTER oldItem;

 

 

 

 

 

删除字段的格式

ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name alter_specification [, alter_specification] ...alter_specification: table_option ... | DROP [COLUMN] col_name

 

eg.

ALTER TABLE myTbl DROP COLUMN uselessItem;