mysql연결 오류

위에의 소스에서 밑에 적혀있는 에러가 발생하네요ㅜ

원인을 잘 모르겠어서, 질문합니다

app_backend | Error: connect ECONNREFUSED 127.0.0.1:3306

app_backend |     at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1128:16)

app_backend |     --------------------

app_backend |     at Protocol._enqueue (/app/node_modules/mysql/lib/protocol/Protocol.js:144:48)

app_backend |     at Protocol.handshake (/app/node_modules/mysql/lib/protocol/Protocol.js:51:23)

app_backend |     at PoolConnection.connect (/app/node_modules/mysql/lib/Connection.js:118:18)

app_backend |     at Pool.getConnection (/app/node_modules/mysql/lib/Pool.js:48:16)

app_backend |     at Pool.query (/app/node_modules/mysql/lib/Pool.js:202:8)

app_backend |     at /app/server.js:42:11

app_backend |     at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5)

app_backend |     at next (/app/node_modules/express/lib/router/route.js:137:13)

app_backend |     at Route.dispatch (/app/node_modules/express/lib/router/route.js:112:3)

app_backend |     at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5) {

app_backend |   errno: -111,

app_backend |   code: 'ECONNREFUSED',

app_backend |   syscall: 'connect',

app_backend |   address: '127.0.0.1',

app_backend |   port: 3306,

app_backend |   fatal: true

app_backend | }