如何在ibatis和Java中处理多个表的sql映射

Question

I am trying to use Ibatis with GWT and I have this scenario, I have databases tables Airport, Terminals and Flights. An airport can have different terminals. A terminal can have one Airport and many flights. And a flight can have one terminal. So the table structure looks like this.

Airport -id -name -terminal_id

Terminals -id -name -flight_id

Flights -id -airline -terminal_id

My select statement looks like this

SELECT airport.name AS Airport,
       terminals.name AS Terminal,
       flights.airline,
FROM airport,
     terminals,
     flights
WHERE airport.terminal_id = terminals.id
  AND terminals.flight_id = flights.id;

What will the sql maps look like to get this result. Where I'm getting confused is the result set is a combination of tables and so the result set isn't a model object of either of the three tables.

Answer 1

Create a custom value object(vo) to suit your need.

<sqlMap namespace="Arrival">
<resultMap id="Arrival" class="com.flight.vo.Arrival">
    <result property="airport" column="Airport" />
    <result property="terminal" column="Terminal" />
    <result property="airline" column="airline"/>
</resultMap>

<select id="retrieveAllArrivals" resultMap="Arrival.Arrival" >
    select airport.name as Airport, terminals.name as Terminal, flights.airline
    FROM airport, terminals, flights 
    WHERE airport.terminal_id = terminals.id 
    AND terminals.flight_id = flights.id
</select>
</sqlMap>