dockerfile：
mysql 資料庫的dockerfile，包含資料的初始化
FROM mysql/mysql-server:5.7
COPY inid.sql /docker-entrypoint-initdb.d
docker-compose.yaml： docker-compose 執行包含ballerina api 以及資料庫
version: "3"
services:
   api:
    image: dalongrong/mysql_demo:v1.0
    ports:
    - "9090:9090"
   mysql:
    build: ./
    ports:
      - 3306:3306
    command: --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci
    environment:
      MYSQL_ROOT_PASSWORD: root
      MYSQL_DATABASE: EMPLOYEE_RECORDS
      MYSQL_USER: gogs
      MYSQL_PASSWORD: dalongrong
      TZ: Asia/Shanghai

inid.sql: 操作依賴的資料庫模型
/* 
 * MySQL Script - initializeDataBase.sql.
 * Create EMPLOYEE_RECORDS database and EMPLOYEES table.
 */

-- Create EMPLOYEE_RECORDS database
CREATE DATABASE IF NOT EXISTS EMPLOYEE_RECORDS;     

-- Switch to EMPLOYEE_RECORDS database
USE EMPLOYEE_RECORDS;

-- create EMPLOYEES table in the database
CREATE TABLE IF NOT EXISTS EMPLOYEES (EmployeeID INT, Name VARCHAR(50), Age INT, SSN INT, PRIMARY KEY (EmployeeID))

mysql_service.bal： 資料庫操作程式碼，集成了docker

import ballerina/config;
import ballerina/http;
import ballerina/log;
import ballerina/mysql;
import ballerina/sql;
import ballerinax/docker;

type Employee record {
    string name;
    int age;
    int ssn;
    int employeeId;
};

// Create SQL endpoint to MySQL database
endpoint mysql:Client employeeDB {
    host: "mysql",
    port: config:getAsInt("DATABASE_PORT", default = 3306),
    name: config:getAsString("DATABASE_NAME", default = "EMPLOYEE_RECORDS"),
    username: config:getAsString("DATABASE_USERNAME", default = "gogs"),
    password: config:getAsString("DATABASE_PASSWORD", default = "dalongrong"),
    dbOptions: { useSSL: false }
};
@docker:Config {
    registry: "dalongrong",
    name: "mysql_demo",
    tag: "v1.0"
}

@docker:CopyFiles {
  // 注意此處mysql jdbc 驅動地址，為了使用簡單，我寫的是絕對路徑，實際上構建之後會copy 到target 目錄，方便映象構建
    files: [{ source: "/Users/dalong/mylearning/ballerina-project/learning/guide/mysql_demo/mysql-connector-java-8.0.13.jar",
            target: "/ballerina/runtime/bre/lib" }]
}

@docker:Expose {}
endpoint http:Listener listener {，
    port: 9090
};

// Service for the employee data service
@http:ServiceConfig {
    basePath: "/records"
}
service<http:Service> EmployeeData bind listener {

    @http:ResourceConfig {
        methods: ["POST"],
        path: "/employee/"
    }
    addEmployeeResource(endpoint httpConnection, http:Request request) {
        // Initialize an empty http response message
        http:Response response;
        Employee employeeData;
        // Extract the data from the request payload
        var payloadJson = check request.getJsonPayload();
        employeeData = check <Employee>payloadJson;

        // Check for errors with JSON payload using
        if (employeeData.name == "" || employeeData.age == 0 || employeeData.ssn == 0 ||
            employeeData.employeeId == 0) {
            response.setTextPayload("Error : json payload should contain
             {name:<string>, age:<int>, ssn:<123456>,employeeId:<int>} ");
            response.statusCode = 400;
            _ = httpConnection->respond(response);
            done;
        }

        // Invoke insertData function to save data in the Mymysql database
        json ret = insertData(employeeData.name, employeeData.age, employeeData.ssn,
            employeeData.employeeId);
        // Send the response back to the client with the employee data
        response.setJsonPayload(ret);
        _ = httpConnection->respond(response);
    }

    @http:ResourceConfig {
        methods: ["GET"],
        path: "/employee/{employeeId}"
    }
    retrieveEmployeeResource(endpoint httpConnection, http:Request request, string
    employeeId) {
        // Initialize an empty http response message
        http:Response response;
        // Convert the employeeId string to integer
        int empID = check <int>employeeId;
        // Invoke retrieveById function to retrieve data from Mymysql database
        var employeeData = retrieveById(empID);
        // Send the response back to the client with the employee data
        response.setJsonPayload(untaint employeeData);
        _ = httpConnection->respond(response);
    }

    @http:ResourceConfig {
        methods: ["PUT"],
        path: "/employee/"
    }
    updateEmployeeResource(endpoint httpConnection, http:Request request) {
        // Initialize an empty http response message
        http:Response response;
        Employee employeeData;
        // Extract the data from the request payload
        var payloadJson = check request.getJsonPayload();
        employeeData = check <Employee>payloadJson;

        if (employeeData.name == "" || employeeData.age == 0 || employeeData.ssn == 0 ||
            employeeData.employeeId == 0) {
            response.setTextPayload("Error : json payload should contain
             {name:<string>, age:<int>, ssn:<123456>,employeeId:<int>} ");
            response.statusCode = 400;
            _ = httpConnection->respond(response);
            done;
        }

        // Invoke updateData function to update data in mysql database
        json ret = updateData(employeeData.name, employeeData.age, employeeData.ssn,
            employeeData.employeeId);
        // Send the response back to the client with the employee data
        response.setJsonPayload(ret);
        _ = httpConnection->respond(response);
    }

    @http:ResourceConfig {
        methods: ["DELETE"],
        path: "/employee/{employeeId}"
    }
    deleteEmployeeResource(endpoint httpConnection, http:Request request, string
    employeeId) {
        // Initialize an empty http response message
        http:Response response;
        // Convert the employeeId string to integer
        var empID = check <int>employeeId;
        var deleteStatus = deleteData(empID);
        // Send the response back to the client with the employee data
        response.setJsonPayload(deleteStatus);
        _ = httpConnection->respond(response);
    }
}

public function insertData(string name, int age, int ssn, int employeeId) returns (json){
    json updateStatus;
    string sqlString =
    "INSERT INTO EMPLOYEES (Name, Age, SSN, EmployeeID) VALUES (?,?,?,?)";
    // Insert data to SQL database by invoking update action
    var ret = employeeDB->update(sqlString, name, age, ssn, employeeId);
    // Use match operator to check the validity of the result from database
    match ret {
        int updateRowCount => {
            updateStatus = { "Status": "Data Inserted Successfully" };
        }
        error err => {
            updateStatus = { "Status": "Data Not Inserted", "Error": err.message };
        }
    }
    return updateStatus;
}

public function retrieveById(int employeeID) returns (json) {
    json jsonReturnValue;
    string sqlString = "SELECT * FROM EMPLOYEES WHERE EmployeeID = ?";
    // Retrieve employee data by invoking select action defined in ballerina sql client
    var ret = employeeDB->select(sqlString, (), employeeID);
    match ret {
        table dataTable => {
            // Convert the sql data table into JSON using type conversion
            jsonReturnValue = check <json>dataTable;
        }
        error err => {
            jsonReturnValue = { "Status": "Data Not Found", "Error": err.message };
        }
    }
    return jsonReturnValue;
}

public function updateData(string name, int age, int ssn, int employeeId) returns (json){
    json updateStatus = {};
    string sqlString =
    "UPDATE EMPLOYEES SET Name = ?, Age = ?, SSN = ? WHERE EmployeeID = ?";
    // Update existing data by invoking update action defined in ballerina sql client
    var ret = employeeDB->update(sqlString, name, age, ssn, employeeId);
    match ret {
        int updateRowCount => {
            if (updateRowCount > 0) {
                updateStatus = { "Status": "Data Updated Successfully" };
            }
            else {
                updateStatus = { "Status": "Data Not Updated" };
            }
        }
        error err => {
            updateStatus = { "Status": "Data Not Updated", "Error": err.message };
        }
    }
    return updateStatus;
}

public function deleteData(int employeeID) returns (json) {
    json updateStatus = {};

    string sqlString = "DELETE FROM EMPLOYEES WHERE EmployeeID = ?";
    // Delete existing data by invoking update action defined in ballerina sql client
    var ret = employeeDB->update(sqlString, employeeID);
    match ret {
        int updateRowCount => {
            updateStatus = { "Status": "Data Deleted Successfully" };
        }
        error err => {
            updateStatus = { "Status": "Data Not Deleted", "Error": err.message };
        }
    }
    return updateStatus;
}