Question

I have several tables that have similar fields, for example, Name and Email address:

TABLE Users (
   Name varchar(255),
   Email varchar(255),
   etc..
)

TABLE Clients (
  Name varchar(255),
  Email varchar(255),
  etc..
)

TABLE Administrators (
  Name varchar(255),
  Email varchar(255),
  etc..
)

I’d like to get a list of all names and email address, and be able to filter out duplicate addresses across tables (i.e. a client and a user may both have the same email address)

Answer 1

Well, you could try:

SELECT DISTINCT Name, Email FROM
  (SELECT Name, Email FROM Users
   UNION
   SELECT Name, Email FROM Clients
   UNION
   SELECT Name, Email FROM Administrators) p