code: function initConnectionPool() {
  
    const connectionSetting = {
      server  : process.env.LIGHTSQLSERVER_HOST,
      userName: process.env.LIGHTSQLSERVER_USER,
      password: process.env.LIGHTSQLSERVER_PASS,
      options : {
        database           : process.env.APPNAME,
        port               : process.env.LIGHTSQLSERVER_PORT,
        rowCollectionOnDone: true // 支持 doneInProc 事件
      }
    };
  
    const poolSetting = {
      min: 5, max: 20, log: true
    };
  
    console.log('SQLServer name: ' + connectionSetting.options.database);
    console.log('SQLServer host: ' + connectionSetting.server);
    console.log('SQLServer port: ' + connectionSetting.options.port);
    console.log('SQLServer user: ' + connectionSetting.userName);
  
    const pool = new ConnectionPool(poolSetting, connectionSetting);
  
    pool.on('error', err => {
      console.error(err);
    });
  
    return pool;
  }
docs: 初始化连接池
  @returns {Object}