以下是模式(schema)的内容。
+---------+---------+
| Employee Table |
+---------+---------+
| EmpId | Name |
+---------+---------+
| 1 | John |
| 2 | Lisa |
| 3 | Mike |
| | |
+---------+---------+
+---------+-----------------+
| Family Table |
+---------+-----------------+
| EmpId | Relationship |
+---------+-----------------+
| 1 | Father |
| 1 | Mother |
| 1 | Wife |
| 2 | Husband |
| 2 | Child |
+---------+-----------------+
+---------+---------+
| Loan Table |
+---------+--------+
| LoanId | EmpId |
+---------+--------+
| L1 | 1 |
| L2 | 1 |
| L3 | 2 |
| L4 | 2 |
| L5 | 3 |
+---------+--------+
- 员工表和家庭表之间存在一对多的关系
- 员工表和贷款表之间存在一对多的关系
我尝试使用连接查询,但是它会返回冗余的行。
现在期望的输出结果为:
+---------+---------+--------------+---------+
| EmpId | Name | RelationShip | Loan |
+---------+---------+--------------+---------+
| 1 | John | Father | L1 |
| - | - | Mother | L2 |
| - | - | Wife | - |
| 2 | Lisa | Husband | L3 |
| - | - | Child | L4 |
| 3 | Mike | - | L5 |
| | | | |
+---------+---------+--------------+---------+