First, ensure that you have the MySQL client installed on your system. This will allow you to connect to your MySQL database and execute SQL queries. You can download it from the official MySQL website and follow the installation instructions for your operating system.

Open a terminal or command prompt and connect to your MySQL database using the MySQL client. Use the command:
```
mysql -u [username] -p
```
Replace `[username]` with your MySQL username. After running the command, you'll be prompted to enter your password. Once authenticated, you can access your database.

Once connected, select the database from which you want to export data. Use the following SQL command:
```
USE [database_name];
```
Replace `[database_name]` with the name of your target database.

Write a SQL query to select the data you wish to export. For example, if you want to export all data from a table called `employees`, you would use:
```
SELECT FROM employees;
```
Make sure your query returns the exact data you need for the JSON file.

Use the MySQL `INTO OUTFILE` command to export the query result to a CSV file. This step helps in organizing data into a structured format that can be easily converted to JSON. Use the following command:
```
SELECT FROM employees INTO OUTFILE '/path/to/file.csv'
FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n';
```
Replace `/path/to/file.csv` with the desired file path for the CSV file. Ensure that the MySQL server has the necessary file permissions for the specified directory.

Once you have the CSV file, use a script to convert it to JSON format. You can write a simple Python script using the built-in `csv` and `json` modules:
```python
import csv
import json

csv_file_path = '/path/to/file.csv'
json_file_path = '/path/to/file.json'

with open(csv_file_path, mode='r') as csv_file:
csv_reader = csv.DictReader(csv_file)
data = [row for row in csv_reader]

with open(json_file_path, mode='w') as json_file:
json.dump(data, json_file, indent=4)
```
Replace `/path/to/file.csv` and `/path/to/file.json` with your respective paths.

Finally, verify the integrity and correctness of the JSON file by opening it in a text editor or using a JSON validator tool. Check that the data structure meets your requirements and that all necessary data points are accurately represented in JSON format.

By following these steps, you can efficiently move data from a MySQL database to a JSON file without relying on third-party tools.