Thursday, May 26, 2011

MYSQL Coalesce Function

Table Contact_Info

Name Business_Phone Cell_Phone Home_Phone
Jeff 531-2531 622-7813 565-9901
Laura NULL 772-5588 312-4088
Peter NULL NULL 594-7477
and we want to find out the best way to contact each person according to the following rules:
1. If a person has a business phone, use the business phone number.
2. If a person does not have a business phone and has a cell phone, use the cell phone number.
3. If a person does not have a business phone, does not have a cell phone, and has a home phone, use the home phone number.
We can use the COALESCE function to achieve our goal:
SELECT Name, COALESCE(Business_Phone, Cell_Phone, Home_Phone) Contact_Phone
FROM Contact_Info;

Name Contact_Phone
Jeff 531-2531
Laura 772-5588
Peter 594-7477

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