use python to create a code to receive a json like atest;and write the key to a mysql which mysql user is testusermysql name is testname and the mysql password is testpassword;

Here's an example code to receive a JSON object and write the key to a MySQL database using Python:

import json
import mysql.connector

# Define the MySQL database connection
db_config = {
    'user': 'testuser',
    'password': 'testpassword',
    'host': 'localhost',
    'database': 'testname'
}

# Connect to the database
conn = mysql.connector.connect(**db_config)

# Define a function to insert the key into the database
def insert_key(key):
    cursor = conn.cursor()
    # Use parameterized query to prevent SQL injection
    query = "INSERT INTO keys (key_name) VALUES (%s)"
    values = (key,)
    cursor.execute(query, values)
    conn.commit()
    cursor.close()

# Receive the JSON object
json_data = '{"a":"test"}'
data = json.loads(json_data)

# Write the key to the database
key = data.keys()[0]
insert_key(key)

# Close the database connection
conn.close()

In this example, we first define the MySQL database connection details and connect to the database using the mysql.connector module. We then define a function insert_key that takes a key as input and inserts it into a table called keys in the database. The function uses a parameterized query to prevent SQL injection.

Next, we receive a JSON object as a string and parse it using the json module. We extract the key from the object and call the insert_key function to write it to the database. Finally, we close the database connection.

Note that this code assumes that a table called keys already exists in the database with a column named key_name. You may need to modify the code to match your specific database schema