Question

我的表学生有列学生ID和学生姓名。我还有表事件，列ID，学生ID和事件。

现在，我想编写一个查询，该查询只返回学生表中具有学生ID的事件表中的行。

我正在运行MySql 5 +。

Answer 1

简单的内部联接：

SELECT DISTINCT(Students.Id, Students.StudentName)
FROM Students
JOIN Events on Students.StudentId = Events.StudentId
ORDER BY Students.StudentName

Answer 2

SELECT * FROM Students
WHERE StudentID IN (SELECT StudentID 
                    FROM Events 
                    WHERE Events.StudentID = Students.StudentID)

Answer 3

除了JOIN和IN之外，你还可以使用EXISTS

SELECT * FROM Students s
WHERE EXISTS  (SELECT * 
                    FROM Events e
                    WHERE e.StudentID = s.StudentID)

Answer 4

你可以写WHERE StudentId IN SELECT StudentId FROM Events。（或至少你可以在SQL Server中）

Answer 5

SELECT DISTINCT s.* FROM Students s INNER JOIN Events e ON e.StudentId = s.id;

Answer 6

select students.ID, students.name 
from students join events on students.id = events.studentID 
group by students.ID, students.name

返回在另一个表中具有匹配记录的行

6 个答案: