Creating Combined Queries

SQL queries are combined using the UNION operator. Using UNION, multiple SELECT statements can be specified, and their results can be combined into a single result set.


Using UNION is simple enough. All you do is specify each SELECT statement and place the keyword UNION between each.

Let's look at an example. You need a report on all your customers in Illinois, Indiana, and Michigan. You also want to include all Fun4All locations, regardless of state. Of course, you can create a WHERE clause that will do this, but this time you'll use a UNION instead.

As I just explained, creating a UNION involves writing multiple SELECT statements. First look at the individual statements:

 SELECT cust_name, cust_contact, ...

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