阅读背景:

sqlite唯一索引多列任意组合

来源:互联网 

I have a table of locations and distances. The distance between A and B is the same as the distance between B and A. Is it possible to add a unique constraint to a table such that the columns when Trying to insert the combination 'B and A' fails if 'A and B' have already been insertedI have a table of locations and distances. The




你的当前访问异常,请进行认证后继续阅读剩余内容。

分享到: