关于索引的sql语句

一 创建索引

1.1 ALTER TABLE

用来创建普通索引，UNIQUE索引，PRIMARY KEY索引

ALTER TABLE table_name ADD INDEX index_name (column_list)
ALTER TABLE table_name ADD UNIQUE (column_list)
ALTER TABLE table_name ADD PRIMARY KEY (column_list)

1.2 CREATE INDEX

对表增加普通索引或UNIQUE索引

CREATE INDEX index_name ON table_name (column_list)
CREATE UNIQUE INDEX index_name ON table_name (column_list)

二 删除索引

2.1 ALTER TABLE

ALTER TABLE table_name DROP INDEX index_name
ALTER TABLE table_name DROP PRIMARY KEY

2.2 DROP INDEX

DROP INDEX index_name ON talbe_name

三 查看索引

show index from tablename;