MYSQL教程mysql alter语句用法实例分享

//增长一个新列
mysql>ALTER TABLE tablename ADD fieldname fieldtype
示例：
ALTER TABLE t2 ADD d TIMESTAMP;
ALTER TABLE infos ADD ex TINYINT NOT NULL DEFAULT '0';MYSQL必读

//重定名列
ALTER TABLE t1 CHANGE a b INTEGER;MYSQL必读

//删除了列
mysql>ALTER TABLE table_name DROP field_name
示例：
ALTER TABLE t2 DROP COLUMN c;MYSQL必读

//改动原字段名称及类型
mysql>ALTER TABLE tablename CHANGE old_field_name new_field_name field_type;MYSQL必读

//转变列的类型
ALTER TABLE t1 CHANGE b b BIGINT NOT NULL;
ALTER TABLE infos CHANGE list list TINYINT NOT NULL DEFAULT '0';MYSQL必读

//重定名表
ALTER TABLE t1 RENAME t2;MYSQL必读

//主键
ALTER TABLE tablename add new_field_id int(5) UNSIGNED DEFAULT 0 NOT NULL anto_increment,ADD PRIMARY KEY (new_field_id);MYSQL必读

//加索引
mysql>ALTER TABLE tablename CHANGE depno depno int(5) NOT NULL;
mysql>ALTER TABLE tablename ADD INDEX 索引名 (字段名1[,字段名2……]);
mysql>ALTER TABLE tablename ADD INDEX emp_name(name);MYSQL必读

//加主症结字的搜索
mysql>ALTER TABLE tablename ADD PRIMARY KEY(id);MYSQL必读

//加唯一限制前提的索引
mysql>ALTER TABLE tablename ADD UNIQUE temp_name2(cardnumber);MYSQL必读

//删除了指定的某索引
mysql>ALTER TABLE tablename DROP INDEX temp_name;MYSQL必读