Question

I have two existing table {PeopleList, EmployeeList}. My problem is how to create a query that joins the other table if a record exist in column but if not, returns the other record of the other column. To make it more clear, i will provide some informations (dummy records) below:

PeopleList Table

AutoInc_ID     EmployeeID     Name
============================================
1              EMP001         Mr. John Doe
2                             Mr. Johnsons
3                             Mrs. Jane Smith
4              EMP002         Mr. Juan Dela Cruz

and

EmployeeList Table

EmployeeID     AliasName     DepartmentID
============================================
EMP001         JDoe          DEP001
EMP002         JDCruz        DEP001
EMP003         Alien         DEP051

and the result i want is:

Result Table

AutoInc_ID     WorkerName
============================================
1              JDoe
2              Mr. Johnsons
3              Mr. Jane Smith
4              JDCruz

Answer 1

SELECT
  PeopleList.AutoInc_ID,
  IFNULL(EmployeeList.AliasName,PeopleList.Name) as WorkerName
FROM
  PeopleList
  LEFT JOIN EmployeeList ON PeopleList.EmployeeID=EmployeeList.EmployeeID
;