Introduction to MySQL BLOB Data Type

BLOB is a data type in MySQL used for storing large amounts of binary data. It can store data with a maximum size of 65,535 bytes, and it can also store data larger than 4GB.

Syntax

When creating a table, you can use the following syntax to define the BLOB data type:

column_name BLOB(size)

Where column_name is the column name, and size is an optional parameter used to specify the maximum length of the BLOB column.

Use Cases

The BLOB data type is suitable for storing any binary data such as images, audio, video, documents, etc. These are typically larger files, and hence require a special data type to store them.

Examples

Here are two examples of using the BLOB data type:

Example 1

Suppose we have a table to store user avatars, which has two columns: id and avatar. Here is the table creation statement:

CREATE TABLE user (
  id INT PRIMARY KEY,
  avatar BLOB
);

Now, let’s insert a user’s avatar into this table:

INSERT INTO user (id, avatar) VALUES
(1, 0xFFD8FFE000104A46494600010101006000600000FFE10016457869660000);

Binary data can be stored as a hexadecimal string using the HEX() function.

Example 2

Suppose we want to store a PDF file, we can create a table with a BLOB column using the following SQL statement:

CREATE TABLE document (
  id INT PRIMARY KEY,
  file_name VARCHAR(255),
  content BLOB
);

Now, we can insert the PDF file into this table:

INSERT INTO document (id, file_name, content)
VALUES (1, 'example.pdf', LOAD_FILE('/path/to/example.pdf'));

Here, the LOAD_FILE() function is used to load the file into the BLOB column.

Conclusion

The BLOB data type is ideal for storing large amounts of binary data such as images, audio, video, documents, etc. By using BLOB columns, you can easily store and manipulate this data in a MySQL database using SQL statements.