mysql - 内连接多个表获取名称而不是 ID

Question

我有4张 table

Table incidences-employees
---------------------------
idIncidenceEmployee PK
idEmployee FK (employee.idemployee)
idMasterIncidence FK (incidence-master.idIncidence)
createdby FK (user-employee.idMongoUser)
authorizedBy FK (user-employee.idMongoUser)

Table incidence-master
---------------------------
idIncidence PK
name

TAble user-employee
--------------------------
idMongoUser PK
idEmployee

Table EMployee
-------------------------
idEmployee Pk
name
lastName

我执行此查询

SELECT employee.name, incidences-master.name, incidences-employees.* 
  FROM employee-incidences 
    INNER JOIN employee ON employee.idEmployee = employee-incidences.idEmployee 
    INNER JOIN incidences-master ON incidences-master.idIncidence = employee-incidences.idIncidenceEmployee

我明白了

Employee name | Incidence name | idIncidenceEmployee | idEmployee | idMasterIncidence | createdby | authorizedBy 
John Doe      | Incidence Name |               1     |    1       |                 5 |    abc123 | abc123

但是在创建并授权时，我得到一个 ID，abc123，我想要的是将 id 与名称相匹配，该 id 位于表 user-employee

    Table user-employee          Table Employee
   ----------------------    -   -------------------
    idMongoUser -> abc123        idEmployee -> 1
    idemployee -> 1              Name -> John Doe

我希望显示 John Doe，而不是 ID。

Answer 1

你可能想要这样的东西:

SELECT employee.name as employeeName, incidences-master.name as incidenceName, e1.name as createdBy, e2.name as authorisedBy
FROM employee-incidences 
INNER JOIN incidences-master ON incidences-master.idIncidence = employee-incidences.idIncidenceEmployee
INNER JOIN employee ON employee.idEmployee = employee-incidences.idEmployee
INNER JOIN user-employee ue1 on ue1.idMongoUser = employee-incidences.createdBy
INNER JOIN employee e1 on e1.idEmployee = ue1.idEmployee
INNER JOIN user-employee ue2 on ue2.idMongoUser = employee-incidences.AuthorizedBy
INNER JOIN employee e2 on e2.idEmployee = ue2.idEmployee

如果存在createdBy或authorizedBy可能为空或null的情况，那么我建议使用Left Joins而不是Inner Joins