mysql中如何删除表上的索引?删除索引?-蒲公英云

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;

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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;

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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
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