Introduction:

Converting data stored as VARCHAR to JSON format is a common task that can enhance data organization and querying capabilities. In this blog, we will discuss the various methods for converting VARCHAR data to JSON in MySQL.

Method 1: Using CONCAT and JSON_OBJECT Functions

Consider a scenario where we have a table named employees with columns id, first_name, and last_name. Our goal is to convert each row into a JSON object.

SELECT CONCAT('{ "id": ', id, ', "first_name": "', first_name, '", "last_name": "', last_name, '" }') AS json_data
FROM employees;

Output:

+------------------------------------------------+
| json_data                                      |
+------------------------------------------------+
| { "id": 1, "first_name": "John", "last_name": "Doe" } |
| { "id": 2, "first_name": "Jane", "last_name": "Smith" } |
+------------------------------------------------+

Method 2: Utilizing CAST and JSON Functions

Let's explore another approach using the CAST function and MySQL's built-in JSON functions.

SELECT CAST(JSON_OBJECT('id', id, 'first_name', first_name, 'last_name', last_name) AS CHAR) AS json_data
FROM employees;

Output:

+---------------------------------------------------+
| json_data                                         |
+---------------------------------------------------+
| {"id": 1, "first_name": "John", "last_name": "Doe"} |
| {"id": 2, "first_name": "Jane", "last_name": "Smith"}|
+---------------------------------------------------+

Method 3: Leveraging the JSON_ARRAYAGG Function

Suppose we need to aggregate multiple rows into a JSON array. The JSON_ARRAYAGG function is here to help.

SELECT JSON_ARRAYAGG(JSON_OBJECT('id', id, 'first_name', first_name, 'last_name', last_name)) AS json_array_data
FROM employees;

Output:

+-----------------------------------------------------------------------------------------------------------------------+
| json_array_data                                                                                                   |
+-----------------------------------------------------------------------------------------------------------------------+
| [{"id": 1, "first_name": "John", "last_name": "Doe"}, {"id": 2, "first_name": "Jane", "last_name": "Smith"}] |
+-----------------------------------------------------------------------------------------------------------------------+

Conclusion:

In this blog, we have explored different methods for converting VARCHAR data to JSON in MySQL. The CONCAT and JSON_OBJECT functions allow us to create individual JSON objects from rows, while the CAST and JSON functions provide an alternative approach. Additionally, the JSON_ARRAYAGG function facilitates the aggregation of rows into a JSON array.