function getDBClient(identifier = "", connectionConfig = {}) {
  switch (identifier) {
    case "mysql":
      const { MySQLConnector } = require("./MySQL");
      return new MySQLConnector(connectionConfig);
    case "postgresql":
      const { PostgresSQLConnector } = require("./Postgresql");
      return new PostgresSQLConnector(connectionConfig);
    case "sql-server":
      const { MSSQLConnector } = require("./MSSQL");
      return new MSSQLConnector(connectionConfig);
    default:
      throw new Error(
        `There is no supported database connector for ${identifier}`
      );
  }
}
@param {SQLEngine} identifier
@param {object} connectionConfig
@returns Database Connection Engine Class for SQLAgent or throws error