IS NOT NULL Operator - (Oracle Misc)

The IS NOT NULL operator is used in Oracle to test for a non-null value. It is used in SQL queries with the WHERE clause to filter results based on the absence of null values.

Syntax

The syntax of the IS NOT NULL operator in Oracle is as follows:

SELECT column_name(s)
FROM table_name
WHERE column_name IS NOT NULL;

Here, column_name(s) refers to the name of the column(s) that you want to retrieve data from, table_name is the name of the table that contains the column(s), and IS NOT NULL is the operator used to filter non-null values.

Example

Consider a table called employees that contains columns for employee_id, first_name, last_name, and phone_number. We can use the IS NOT NULL operator to retrieve only the rows that have a non-null value for the phone_number column, as shown in the following example:

SELECT first_name, last_name
FROM employees
WHERE phone_number IS NOT NULL;

Output

The output of the above SQL query will be a list of all employees' first and last names who have non-null phone numbers.

Explanation

In the above example, we are selecting the first_name and last_name columns from the employees table, but only for the rows where the phone_number column has a non-null value. The IS NOT NULL operator is used to filter out any rows where the phone_number column contains a null value.

Use

The IS NOT NULL operator is useful when you want to retrieve only the rows with non-null values from a database table. This can be helpful when dealing with large datasets where some values may be missing.

Important Points

• The IS NOT NULL operator is used to filter out rows that have a null value in a specified column.
• The IS NOT NULL operator is used in the WHERE clause of SQL queries.
• The IS NOT NULL operator returns only the rows that have a non-null value in the specified column.

Summary

In summary, the IS NOT NULL operator is a useful tool for filtering out null values from a database table. It can be used in SQL queries to retrieve only the rows with non-null values in a specified column. This is particularly helpful when working with large datasets where null values may be present.