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MySQL

Test data in MySQL or MySQL-compatible databases (e.g. MariaDB).

1. Install​

uv tool install --python python3.11 --upgrade 'datacontract-cli[mysql]'

See Installation for pip, pipx, and Docker.

2. Set credentials​

Create a .env file in your working directory (or export the variables):

# .env
DATACONTRACT_MYSQL_USERNAME=root
DATACONTRACT_MYSQL_PASSWORD=mysecretpassword

3. Create a contract from your tables​

Dump the DDL of a table and import it:

mysqldump --no-data mydb orders > orders.sql
datacontract import sql --source orders.sql --dialect mysql --output datacontract.yaml

The SQL import can't know your connection details, so it writes a servers block with placeholder values. Open datacontract.yaml and fill in your server:

servers:
  - server: mysql
    type: mysql
    host: localhost
    port: 3306
    database: mydb

4. Test the actual data​

datacontract test datacontract.yaml
🟢 data contract is valid. Run 24 checks. Took 2.1 seconds.

5. Let it catch a violation​

The contract becomes valuable when it detects drift. Tighten an expectation — for example, add a quality rule to a schema in datacontract.yaml:

schema:
  - name: orders
    # ...
    quality:
      - type: sql
        description: No order has a negative total
        query: SELECT COUNT(*) FROM orders WHERE order_total < 0
        mustBe: 0

Run datacontract test datacontract.yaml again: every violation is listed as an error, and the command exits with code 1 — ready for CI/CD scheduling so you catch drift before your consumers do.

Reference​

All authentication options and the data type mappings: MySQL Reference.

Troubleshooting​

  • Access denied for user — check the two environment variables above and the user's host restrictions ('user'@'%' vs 'user'@'localhost').
  • Can't connect to MySQL server — host/port in the servers block are wrong, or the server doesn't accept remote connections (bind-address).