Oracle WHERE Clause

Summary: in this tutorial, you will learn how to use the Oracle WHERE clause to specify a condition for filtering rows returned by a query.

Introduction to Oracle WHERE clause

The WHERE clause specifies a search condition for rows returned by the SELECT statement. The following illustrates the syntax of the WHERE clause:

SELECT select_list FROM table_name WHERE search_condition ORDER BY sort_expression;
Code language: SQL (Structured Query Language) (sql)

The WHERE clause appears after the FROM clause but before the ORDER BY clause. Following the WHERE keyword is the search_condition that defines a condition that returned rows must satisfy.

Besides the SELECT statement, you can use the WHERE clause in the DELETE or UPDATE statement to specify which rows to update or delete.

Oracle WHERE examples

See the following products table in the sample database:

products table

A) Selecting rows by using a simple equality operator

The following example returns only products whose names are 'Kingston':

SELECT product_name, description, list_price, category_id FROM products WHERE product_name = 'Kingston';
Code language: SQL (Structured Query Language) (sql)

The following picture illustrates the result:

Oracle WHERE - equality example

In this example, Oracle evaluates the clauses in the following order:FROM WHERE and SELECT

  1. First, the FROM clause specified the table for querying data.
  2. Second, the WHERE clause filtered rows based on the condition e.g., product_name = 'Kingston').
  3. Third, the SELECT clause chose the columns that should be returned.

B) Select rows using comparison operator

Besides the equality operator, Oracle provides you with many other comparison operators illustrated in the following table:

Operator
Description
=Equality
!=,<>Inequality
>Greater than
<Less than
>=Greater than or equal to
<=Less than or equal to
INEqual to any value in a list of values
ANY/ SOME / ALLCompare a value to a list or subquery. It must be preceded by another operator such as =, >, <.
NOT INNot equal to any value in a list of values
[NOT] BETWEEN and mEquivalent to [Not] >= n and <= y.
[NOT] EXISTSReturn true if subquery returns at least one row
IS [NOT] NULLNULL test

For example, to get products whose list prices are greater than 500, you use the following statement:

SELECT product_name, list_price FROM products WHERE list_price > 500;
Code language: SQL (Structured Query Language) (sql)
Oracle WHERE - multiple conditions example

C) Select rows that meet some conditions

To combine conditions you can use the AND, OR and NOT logical operators.

For example, to get all motherboards that belong to the category id 1 and have list prices greater than 500, you use the following statement:

SELECT product_name, list_price FROM products WHERE list_price > 500 AND category_id = 4;
Code language: SQL (Structured Query Language) (sql)

The result set includes only motherboards whose list prices are greater than 500.

Oracle WHERE - comparison operator example

D) Selecting rows that have a value between two values

To find rows that have a value between two values, you use the BETWEEN operator in the WHERE clause.

For example, to get the products whose list prices are between 650 and 680, you use the following statement:

SELECT product_name, list_price FROM products WHERE list_price BETWEEN 650 AND 680 ORDER BY list_price;
Code language: SQL (Structured Query Language) (sql)

The following picture illustrates the result set:

oracle where with between operator

Note that the following expressions are equivalent:

list_price BETWEEN 650 AND 680 list_price >= 650 AND list_price <= 680

E) Selecting rows that are in a list of values

To query rows that are in a list of values, you use the IN operator as follows:

SELECT product_name, category_id FROM products WHERE category_id IN(1, 4) ORDER BY product_name;
Code language: SQL (Structured Query Language) (sql)

The following illustrates the result:

Oracle WHERE - IN Operator example

The expression:

category_id IN (1, 4)
Code language: SQL (Structured Query Language) (sql)

is the same as:

category_id = 1 OR category_id = 4
Code language: SQL (Structured Query Language) (sql)

F) Selecting rows which contain value as a part of a string

The following statement retrieves product whose name starts with Asus:

SELECT product_name, list_price FROM products WHERE product_name LIKE 'Asus%' ORDER BY list_price;
Code language: SQL (Structured Query Language) (sql)

In this example, we used the LIKE operator to match rows based on the specified pattern.

In this tutorial, you have learned how to use the Oracle WHERE clause to specify a search condition for rows returned by a query.

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