mysql - 查询返回错误结果，预期一行但得到全部

Question

我下面的语句返回表的所有结果，而不是仅返回匹配的 n1。我已附上结果的屏幕截图。我所期待的只是第一行。有人可以帮助我了解这里发生了什么吗？ Result of the Query attached

Create View Proj_Display AS
select * from Proj_d
Where "n" in (Select Student from proj_d);

Answer 1

Create View Proj_Display AS
select * from Proj_d
Where "n1" in (Select Student from proj_d);

您现在的查询检查表 proj_d 中是否存在值“n1”。这始终是正确的。所以我猜你想要这样的东西:

Create View Proj_Display AS
select * from Proj_d
Where Student  in (Select Student from proj_d WHERE Student = 'n1');

但是您可以立即执行此操作，而无需使用子查询:

Create View Proj_Display AS
select * from Proj_d
Where Student  = 'n1'

但是您可能需要提供更多您想要的信息