Question

I’ve got 3 tables linked together using foreign keys. One of the tables contains data that may be null, but I still want it displayed. I’ve also got multiple conditions worked in.

This is what I have so far, but it doesn’t work:

SELECT ord.OrdNo, ord.OrdDate, cu.CustNo, cu.CustFirstName, cu.CustLastName, em.EmpNo, em.EmpFirstName, em.EmpLastName
FROM OrderTbl ord, Customer cu, Employee em
WHERE cu.CustNo=ord.CustNo
AND em.EmpNo=ord.EmpNo (+)
AND ( OrdDate BETWEEN '01-Jan-04'
AND '31-Jan-04')
AND cu.CustState = 'CO'

Basically, the employee info might be null on the order table, but I still want the entries displayed. Any help would be appreciated, since I’ve only started learning SQL.

Edit: There were no errors in running this above query. It’s just that I was missing results that had null fields.

Answer 1

Pleaes use JOINS, to be precise in your case LEFT JOIN to show all Employees’ orders:

SELECT ord.OrdNo, ord.OrdDate, cu.CustNo, cu.CustFirstName, cu.CustLastName, 
em.EmpNo, em.EmpFirstName, em.EmpLastName
FROM OrderTbl ord
  LEFT JOIN 
  Customer cu
    ON  cu.CustNo=ord.CustNo
    AND cu.CustState = 'CO'
  LEFT JOIN 
  Employee em
    ON  em.EmpNo=ord.EmpNo
WHERE OrdDate BETWEEN '2004-01-01' 
                  AND '2004-01-31'
;

Reference:

Visual Representation of JOINs: