MySQL BINARY Data Type

Introduction

In this chapter, we will learn about the BINARY data type in MySQL. The BINARY data type is used to store binary strings. It is particularly useful for storing fixed-length binary data, such as hashes, binary flags, or any other binary data that needs to be stored exactly as is. We will cover the syntax for defining BINARY columns, examples, and important considerations for using BINARY in MySQL.

Syntax

The basic syntax for defining a BINARY column in MySQL is:

BINARY(length)

• length: Specifies the fixed length of the binary string. The length can be any value from 0 to 255.

Example

Here is an example of how to define a BINARY column in a table:

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50) NOT NULL,
    password_hash BINARY(64)
);

In this example, password_hash is defined as a BINARY(64) column to store a 64-byte binary hash of user passwords.

Full Example

Let’s go through a complete example where we create a database and a table with BINARY columns, insert data, and demonstrate their usage.

1. Create a Database:

CREATE DATABASE secure_app;

2. Select the Database:

USE secure_app;

3. Create the Users Table with BINARY Columns:

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50) NOT NULL,
    password_hash BINARY(64)
);

4. Insert Data into the Users Table:

INSERT INTO users (username, password_hash) VALUES
('rahul_sharma', UNHEX(SHA2('password123', 256))),
('priya_singh', UNHEX(SHA2('securepass', 256))),
('amit_kumar', UNHEX(SHA2('mypassword', 256))),
('neha_verma', UNHEX(SHA2('admin1234', 256))),
('sahil_mehta', UNHEX(SHA2('passw0rd', 256)));

5. Query the Users Table:

SELECT id, username, HEX(password_hash) as password_hash FROM users;

Output

In this example, the password_hash column is defined as BINARY to store binary hashes of user passwords.

Using BINARY Values in Queries

You can use BINARY values in queries to filter and manipulate binary data.

Example: Query Users by Password Hash

SELECT id, username FROM users WHERE password_hash = UNHEX(SHA2('password123', 256));

Output

Example: Query Users and Convert Binary Hash to HEX

SELECT id, username, HEX(password_hash) as password_hash FROM users;

Output

Important Considerations

• Fixed Length: The BINARY data type is best used for columns where the length of the binary string is consistent. If the length varies, consider using the VARBINARY data type.
• Storage Requirements: The BINARY data type always uses the specified length, even if the actual binary data is shorter. This can lead to wasted storage space if the binary data is often shorter than the defined length.
• Padding: BINARY values are padded with \0 (null bytes) to the specified length. When retrieving BINARY values, these padding bytes are included in the value.
• Performance: The BINARY data type can be more efficient than VARBINARY for short, fixed-length binary strings because it avoids the overhead of variable-length storage.

Conclusion

The BINARY data type is useful for storing fixed-length binary strings in MySQL. This chapter covered the syntax for defining BINARY columns, provided a full example with different binary attributes, and discussed important considerations.