索引
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3.??????索引的相关操作
上一讲我们介绍了索引的作用和种类,这一讲我们谈谈索引的相关操作!
1)????添加索引
前面已经有所介绍,这里总结一下
添加主键索引
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- create?table?aaa??
- (id?int?unsigned?primary?key?auto_increment?,??
- name?varchar(32)?not?null?defaul?‘’);??
- ??
- alter?table?表名?add?primary?key?(列名);??
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添加普通索引
- create?index?索引名?on?表?(列名1,列名2);??
添加唯一索引
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- create?table?ddd(id?int?primary?key?auto_increment?,?name?varchar(32)?unique);??
- ??
- create?unique?index?索引名??on?表名?(列表..);??
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添加全文索引
- CREATE?TABLE?articles?(??
- ???????id?INT?UNSIGNED?AUTO_INCREMENT?NOT?NULL?PRIMARY?KEY,??
- ???????title?VARCHAR(200),??
- ???????body?TEXT,??
- ???????FULLTEXT?(title,body)??
- ?????)engine=myisam?charset?utf8;??
- ??
- ALTER?TABLE?articles?ADD?FULLTEXT?(title,body);??
2)????查询索引
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- show?index?from?emp\G??
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3)????删除索引
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- drop?index?索引名称?on?表名;??
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4)????修改索引
先删除,再创建