For example I have 3 tables: First like 'Users', where for every single user stored his name. Second - 'Location', where addresses of users stored - typically 1 address for 1 user. And third - 'Messages' - where every user typically have a bunch of records.For example I have 3 tables: First like 'Users'
阅读背景：
SQL优化多个连接结果中的重复记录
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