mysql中如何删除表上的索引?删除索引?

需求描述:

　　今天在做SQL的优化的时候,想要把mysql中某个表上的索引删除掉,突然忘记语法了,找到帮助,在此记录下

操作过程:

1.查看表上的索引

show index from ti_o_sms;

备注:通过以上的查询,TI_O_SMS_IDX是一个复合索引.

2.删除这个复合索引

drop index TI_O_SMS_idx on ti_o_sms;

备注:执行完删除语句之后,再次查询,表上的复合索引已经被删除了.

3.通过help命令查看删除索引的语法

mysql> help drop index
Name: 'DROP INDEX'
Description:
Syntax:
DROP INDEX index_name ON tbl_name
    [algorithm_option | lock_option] ...

algorithm_option:
    ALGORITHM [=] {DEFAULT|INPLACE|COPY}

lock_option:
    LOCK [=] {DEFAULT|NONE|SHARED|EXCLUSIVE}

DROP INDEX drops the index named index_name from the table tbl_name.
This statement is mapped to an ALTER TABLE statement to drop the index.
See [HELP ALTER TABLE].

To drop a primary key, the index name is always PRIMARY, which must be
specified as a quoted identifier because PRIMARY is a reserved word:

DROP INDEX `PRIMARY` ON t;

URL: http://dev.mysql.com/doc/refman/5.7/en/drop-index.html

mysql> 

 

文档创建时间:2018年8月16日10:13:22