Can We Use BOOLEAN Data Type in SQL?


Heather Bennett

When working with SQL databases, one of the most common data types used is the BOOLEAN data type. In this article, we will explore the concept of BOOLEAN in SQL and discuss how it can be used effectively in database management.

Understanding BOOLEAN Data Type

In SQL, the BOOLEAN data type represents a logical value that can be either true or false. It is commonly used to store binary values or to represent conditions in SQL queries.

Creating a Table with BOOLEAN Columns

To use the BOOLEAN data type in SQL, we need to create a table with columns of this type. Let’s consider an example where we want to create a table to store information about books in a library. We might have columns such as “title,” “author,” and “available” to indicate whether a book is available for borrowing.

To create this table, we can use the following SQL statement:

    title VARCHAR(100),
    author VARCHAR(100),
    available BOOLEAN

The “available” column has been defined as a BOOLEAN data type, which means it can only hold true or false values.

Inserting Data into BOOLEAN Columns

Once we have created our table with BOOLEAN columns, we can insert data into these columns using INSERT statements. For example:

INSERT INTO books (title, author, available)
VALUES ('The Great Gatsby', 'F. Scott Fitzgerald', true);

INSERT INTO books (title, author, available)
VALUES ('To Kill a Mockingbird', 'Harper Lee', false);

In the above code snippet, we are inserting two rows into our “books” table. The first row has the book title ‘The Great Gatsby’ written by ‘F.

Scott Fitzgerald’ and is marked as available (true). The second row represents the book ‘To Kill a Mockingbird’ written by ‘Harper Lee’ and is marked as not available (false).

Using BOOLEAN in SQL Queries

BOOLEAN data types are incredibly useful when it comes to writing SQL queries that involve conditions or filtering based on logical values. Let’s take a look at a few examples:

  • Example 1: Retrieve all books that are currently available:
  • SELECT * FROM books WHERE available = true;
  • Example 2: Retrieve all books that are not available:
  • SELECT * FROM books WHERE available = false;
  • Example 3: Update the availability of a book:
  • UPDATE books SET available = true WHERE title = 'The Great Gatsby';

In Example 1 and Example 2, we use the BOOLEAN column “available” to filter the results based on whether the book is currently available or not. In Example 3, we update the availability of a specific book by setting its “available” value to true.


The BOOLEAN data type in SQL provides an efficient way to handle logical values and conditions in database management. It allows us to store and manipulate binary data effectively, making it an essential tool for SQL developers.

In this article, we discussed how to create tables with BOOLEAN columns, insert data into these columns, and use BOOLEAN values in SQL queries. By leveraging the power of BOOLEAN data types, you can enhance the functionality of your SQL databases and improve your query capabilities.

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