Concatenate 3 tables into a view.

Question

Hello,
I'm relatively new to SQL as it has been many years since taking the PL/SQL course at Oracle. Using Oracle 9i.
I am attempting to build a view that is simply a concatenation of three tables. I guess the best way to explain is an example.
Lets say I have three tables, one for each of three cities with employee names in them.
i.e.
Table Ottawa Table Halifax Table Edmonton
first last first last first last
john smith john denver Tom Cochrane
jane doe rod stewart Van Halen
I want my view to look like (order of names doesn't matter):
first last
john smith
jane doe
john denver
rod stewart
Tom Cochrane
Van Halen
I tried
CREATE or UPDATE VIEW emp AS
(SELECT first, last FROM ottawa;
SELECT first, last FROM halifax;
SELECT first, last FROM edmonton)
But with no luck. I know that multiple SELECT statements work with a start file, but that doesn't seem to do me any good in this situation. Any help on this would be appreciated.
Thank you

Answer 1

Hi,
Welcome to the forum!
You want UNION ALL:
SELECT  first, last  FROM ottawa      UNION ALL
SELECT  first, last  FROM halifax     UNION ALL
SELECT  first, last  FROM edmonton;UNION (or UNION ALL) presents the results of two or more queries as a single result set.
It would probably be a better design to have just one table, with columns first, last and city, like this:
first   last    city
john    smith   Ottawa
jane    doe     Ottawa
john    denver  Halifax
...You could create views that included just one city, if you needed them.
Edited by: Frank Kulash on Jul 17, 2009 4:31 PM