数据存在(重复)检测
暂时能想到三个方法
交给数据库处理，数据库设置 UNIQUE
交给数据库处理，每次 INSERT 之前执行 SELECT, 但这样随着数据增大 SELECT 次数会不断增加
交给语言处理，将已有数据存在数组中，用 in_array 等处理，但是随着数据增加数组会变得非常庞大
暂时想到的三个处理方法，觉得都不是很好
你们会用怎样的方案呢
回复内容：
暂时能想到三个方法
交给数据库处理，数据库设置 UNIQUE
交给数据库处理，每次 INSERT 之前执行 SELECT, 但这样随着数据增大 SELECT 次数会不断增加
交给语言处理，将已有数据存在数组中，用 in_array 等处理，但是随着数据增加数组会变得非常庞大
暂时想到的三个处理方法，觉得都不是很好
你们会用怎样的方案呢
请用UNIQUE的索引，在插入时使用INSERT IGNORE语法
好处是:
性能不差，
INSERT IGNORE会自动在UNIQUE的索引里检查是否有重复项，由于是索引，所以比较发生在内存里好用，成功就返回插入行数，失败就返回0
在你的数据量达到几百万之前，这个方法都还是比较可靠的
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