SQL加入相关问题

Question

我遇到SQL连接问题.

我有一个表EMPLOYEE与EmpID, FirstName, LastName, Email, Phone

我有另外一个OTHERNAME有2个字段的表"Name" & "OtherName".

此表包含查找值,例如"James", "Jim"; "Thomas", "Tom"; "Steven", "Steve".

我想写一个返回行的查询

EmpID, FirstName, LastName, Email, Phone, OtherName
where Employee.Firstname = OTHERName.Name

Answer 1

Select e.EmpID, e.FirstName, e.LastName, e.Email, e.Phone, o.OtherName
From Employee e
Left Outer Join OtherName o on e.FirstName = o.Name

从您的评论中听起来您实际上想要一个外部联接.

(来自注释)外部联接将返回所有员工,如果有其他名称则返回其他名称,否则其他名称将是您可以在代码中处理的空值.内部联接将结果限制为仅具有匹配记录的员工.