_exec(queryString) {
		if (!this.connection) {
			throw new Error('No Connection for the model.');
		}

		let operation = {
			isAltered: (this.opType !== 'select') ? true : false,
			type: this.opType,
			pk: this.primaryKey
		};

		//reset query object
		if (!this._query.iterative) {
			this._query = {};
		}

		const connectionType = this.connection.getConnectionType();
		const db = dbInit(connectionType);

		return db.exec(this.connection.getConnection(), queryString, operation);
	}
/**
	 * executing query after all essential query params is set
	 * @param string
	 */
executing query after all essential query params is set
@param string
executing query after all essential query params is set @param string
_exec(queryString) {
		if (!this.connection) {
			throw new Error('No Connection for the model.');
		}
		let operation = {
			isAltered: (this.opType !== 'select') ? true : false,
			type: this.opType,
			pk: this.primaryKey
		};
		if (!this._query.iterative) {
			this._query = {};
		}
		const connectionType = this.connection.getConnectionType();
		const db = dbInit(connectionType);
		return db.exec(this.connection.getConnection(), queryString, operation);
	}
_exec ( queryString ) { if ( ! this . connection ) { throw new Error ( 'No Connection for the model.' ) ; } let operation = { isAltered : ( this . opType !== 'select' ) ? true : false , type : this . opType , pk : this . primaryKey } ; if ( ! this . _query . iterative ) { this . _query = { } ; } const connectionType = this . connection . getConnectionType ( ) ; const db = dbInit ( connectionType ) ; return db . exec ( this . connection . getConnection ( ) , queryString , operation ) ; }
executing query after all essential query params is set
 @param string
executing query after all essential query params is set @param string
//reset query object