PostgreSQL: IN Condition

In this PostgreSQL post explains how to use the PostgreSQL IN condition with syntax and examples.

Description

The PostgreSQL IN condition is used to help reduce the need to use multiple OR conditions in a SELECT, INSERT, UPDATE, or DELETE statement.

Syntax

The syntax for the IN condition in PostgreSQL is:

expression IN (value1, value2, .... value_n);

OR

expression IN (subquery);

Parameters or Arguments

expression

A value to test.

value1, value2..., or value_n

The values to test against expression.

subquery

This is a SELECT statement whose result set will be tested against expression. If any of these values matches expression, then the IN condition will evaluate to true.

Note

• The PostgreSQL IN condition will return the records where expression is value1, value2..., or value_n.
• The PostgreSQL IN condition is also called the PostgreSQL IN operator.

Example - With Character

Let's look at a PostgreSQL IN condition example using character values.

The following is a PostgreSQL SELECT statement that uses the IN condition to compare character values:

SELECT *
FROM suppliers
WHERE supplier_name IN ('Apple', 'Samsung', 'RIM');

This PostgreSQL IN condition example would return all rows from the suppliers table where the supplier_name is either 'Apple', 'Samsung' or 'Asus'. Because the * is used in the SELECT, all fields from the suppliers table would appear in the result set.

The above IN example is equivalent to the following SELECT statement:

SELECT *
FROM suppliers
WHERE supplier_name = 'Apple'
OR supplier_name = 'Samsung'
OR supplier_name = 'RIM';

As you can see, using the PostgreSQL IN condition makes the statement easier to read and more efficient.

Example - With Numeric

Next, let's look at a PostgreSQL IN condition example using numeric values.

For example:

SELECT *
FROM employees
WHERE employee_id IN (300, 301, 500, 501);

This PostgreSQL IN condition example would return all employees where the employee_id is either 300, 301, 500, or 501.

The above IN example is equivalent to the following SELECT statement:

SELECT *
FROM employees
WHERE employee_id = 300
OR employee_id = 301
OR employee_id = 500
OR employee_id = 501;

Example - Using NOT operator

Finally, let's look at an IN condition example using the NOT operator.

For example:

SELECT *
FROM suppliers
WHERE supplier_name NOT IN ('Apple', 'Samsung', 'RIM');

This PostgreSQL IN condition example would return all rows from the suppliers table where the supplier_name is not 'Apple', 'Samsung', or 'RIM'. Sometimes, it is more efficient to list the values that you do not want, as opposed to the values that you do want.