The MySQL JSON_QUOTE function is used to surround a JSON string with double quotation marks and escape any special characters within the string. This is particularly useful when you need to create valid JSON strings within SQL queries or when working with JSON data in MySQL.

The primary purpose of JSON_QUOTE is to prepare strings for inclusion within JSON documents. By properly quoting and escaping special characters, the function ensures that the string adheres to JSON syntax and doesn’t introduce any unexpected errors during parsing or manipulation.

Syntax

The basic syntax of the JSON_QUOTE function is as follows:

JSON_QUOTE(json_string)

json_string: The string to be quoted. It can be a literal string or a column that contains a string.

Example

Let’s consider a simple example where you have a table named products with a column named product_name:

CREATE TABLE products (
    product_id INT,
    product_name VARCHAR(255)
);

INSERT INTO products (product_id, product_name)
VALUES (1, 'Smartphone'),
       (2, 'Laptop'),
       (3, 'Tablet');

Now, suppose you want to retrieve the product names as a JSON array. You can use the JSON_ARRAY function along with JSON_QUOTE to achieve this:

SELECT 
JSON_ARRAY(
JSON_QUOTE(product_name)
) AS json_product_names
FROM products;

In this example, JSON_QUOTE(product_name) is used to quote each product name, and then JSON_ARRAY is used to create an array with these quoted strings. The result will be a JSON array:

+------------------------+
| json_product_names     |
+------------------------+
| ["Smartphone"]         |
| ["Laptop"]             |
| ["Tablet"]             |
+------------------------+

This ensures that the product names are properly formatted as JSON strings, suitable for use in a larger JSON document or response.

The JSON_QUOTE() function plays a significant role in handling JSON data within MySQL databases. It ensures that strings are properly formatted for inclusion in JSON documents, preventing syntax errors and maintaining the integrity of JSON data.