UnhandledPromiseRejectionWarning: Error: Can’t reach database server at `localhost`:`3306`の解決方法

npm run startでNestJSのプロジェクトを起動しようとしたら、以下のようなエラーが発生。

(node:1993) UnhandledPromiseRejectionWarning: Error: Can't reach database server at `localhost`:`3306`

Please make sure your database server is running at `localhost`:`3306`.
    at /Users/asakura/AsakuraProjects/Pens_Mate/pens-mate/node_modules/@prisma/client/runtime/index.js:25078:22
(node:1993) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:1993) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.


$ mysql.server start
Starting MySQL