Sams Teach Yourself SQL in 10 Minutes

Combining WHERE Clauses

All the WHERE clauses introduced in Lesson 4, "Filtering Data," filter data using a single criteria. For a greater degree of filter control, SQL lets you specify multiple WHERE clauses. These clauses may be used in two ways: as AND clauses or as OR clauses.

Using the AND Operator

To filter by more than one column, you use the AND operator to append conditions to your WHERE clause. The following code demonstrates this:

SELECT prod_name, prod_price
FROM Products
WHERE vend_id = 'DLL01' AND prod_price <= 4;

The above SQL statement retrieves the product name and price for all products made by vendor DLL01 as long as the price is $4 or less. The WHERE clause in this SELECT statement is made up of two conditions, and the ...