检索sql查询

Question

SQL 查询检索以下条件。有两列，一列以 user_id 作为主键，另一列作为经理键。我想检索查询，以便它显示经理密钥以及用户 ID 作为经理 1、经理 2

Answer 1

尝试一下：您可以使用自连接来实现此目的

SELECT e1.name, e1.managerid, e2.name, e2.user_id
FROM Employee e1
INNER JOIN Employee e2
ON e1.managerid= e2.user_id

Answer 2

尝试一下，您可以使用相同的方法来查找层次结构：

SELECT e1.name AS EmployeeName
    ,e1.user_id AS USERID
    ,e2.name AS ManagerName1
    ,e2.user_id AS ManagerID1
    ,e3.name AS ManagerName2
    ,e3.user_id AS ManagerID2
FROM Employee e1
LEFT JOIN Employee e2
    ON e1.managerid = e2.user_id
LEFT JOIN Employee e3
    ON e2.managerid = e3.user_id