mysql中如何刪除表上的索引?刪除索引?

需求描述:

　　今天在做SQL的優化的時候,想要把mysql中某個表上的索引刪除掉,突然忘記語法了,找到幫助,在此記錄下

操作過程:

1.查看表上的索引

show index from ti_o_sms;

備注:通過以上的查詢,TI_O_SMS_IDX是一個復合索引.

2.刪除這個復合索引

drop index TI_O_SMS_idx on ti_o_sms;

 

備注:執行完刪除語句之后,再次查詢,表上的復合索引已經被刪除了.

3.通過help命令查看刪除索引的語法

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> 

 

文檔創建時間:2018年8月16日10:13:22