Question

I have 3 tables

[contact]
------------------
cID (PRIMARY KEY, INT) || name || lastupdate (TIMESTAMP)

[phone]
----------------------
cID (FOREIGN KEY, linked to contact.cID) || phonenumber || pID (phone number ID, since each contact can have many numbers)

[email]
------------------------
cID (FOREIGN KEY) || email

I need to make a select query that will fetch all the cID of each contact, their name, their phone number if the pID is 1 and their email all in one table.
So the output would look like this for example.

cID   |   name             |   phone1  |  email
----------------------------------------------
45    |  John Smith         |  1234567  |  [e-mail]
46    |  Darth Vader        |  9999999  |  [e-mail]
47    |  Yoda               |  1236547  |  
-----------------------------------------------------------------------------

I tried doing it like this

SELECT contact.cID, name, phone, email FROM contact, phone, email 
WHERE contact.cID = phone.cID AND contact.cID = email.cID AND phone.pID = 1;

This almost does it, but if a contact doesn’t have either a phone number or an email by their name then they’ll be left out.
I need to show all the contacts, regardless weather they have an email or a phone number in the database.

How can I accomplish this?

Answer 1

Select c.cID, C.name, P.phone As phone1, E.email
From contact As C
    Left Join phone As P
        On P.cID = C.cID
            And P.pID = 1
    Left Join email As E
        On E.cID = C.cID

In short, you need to put the criteria for the pID = 1 in the ON clause when joining phone to contact. In additon, you need to use Left Joins to handle the case where they do not have a phone or email.