Question

我对旧的JOIN声明并不满意，并寻求一些友好的帮助。我有两个表，比如表Employee：

   LastName DepartmentID
Rafferty    31
Jones   33
Steinberg   33
Robinson    34
Smith   34
John    NULL

和表格Department：

DepartmentID    DepartmentName
31  Sales
33  Engineering
34  Clerical
35  Marketing

如果我想将结果返回到DepartmentID=31并且只返回Employee.DepartmentID = Department.DepartmentID的结果，那么返回的结果将如下所示：

Employee.LastName   Employee.DepartmentID   Department.DepartmentName
Rafferty    31  Sales

（我们可以删除其中一个DepartmentID，因为它们是相同的） - 将完成该任务的SQL语句是什么？

由于

Answer 1

SELECT e.LastName, e.DepartmentID, d.DepartmentName
FROM Employee e
INNER JOIN Department d ON d.DepartmentID = e.DepartmentID
WHERE d.DepartmentID = 31

Answer 2

有隐喻的鱼：

SELECT * FROM员工INNER JOIN部门在employee.departmentId = department.departmentId WHERE departmentId = 31

这是隐喻性的钓鱼课程：

http://www.w3schools.com/sql/sql_join.asp（只需按“下一步”）

Answer 3

SELECT e.LastName, e.DeparmentID, d.DepartmentName
FROM employee AS e INNER JOIN department AS d ON e.DepartmentID = e.DepartmentID
WHERE e.DepartmentID = 31

我们将使用INNER JOIN使用ON部分匹配每个表中的记录 - ＆gt;等同于两个表之间的离开值。

MySQL JOIN语句交叉连接？

3 个答案: