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mysql的唯一索引UNIQUE

WBOY
Release： 2016-06-07 17:23:48
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创建唯一索引的目的不是为了提高访问速度，而只是为了避免数据出现重复。唯一索引可以有多个但索引列的值必须唯一，索引列的值允许有空值。如果能确定某个数据列将只包含彼此各不相同的值，在为这个数据列创建索引的时候就应该使用关键字UNIQUE，把它定义为一个唯一索引。


创建唯一索的方法

操作表

CREATE TABLE `wb
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Related labels：
create nbsp table unique
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