SQL Mapping Files

The Heart of iBATIS

SQL mapping files hold named statements, parameter maps and result maps. They were the pattern MyBatis inherited almost unchanged.

<!DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
  "http://ibatis.apache.org/dtd/sql-map-2.dtd">
<sqlMap namespace="Customer">

  <resultMap id="customerResult" class="com.example.app.domain.Customer">
    <result property="id" column="id"/>
    <result property="name" column="name"/>
    <result property="email" column="email"/>
    <result property="city" column="city" nullValue="unknown"/>
  </resultMap>

  <select id="getCustomer" parameterClass="long" resultMap="customerResult">
    SELECT id, name, email, city FROM customers WHERE id = #id#
  </select>

  <insert id="insertCustomer" parameterClass="com.example.app.domain.Customer">
    INSERT INTO customers (name, email, city)
    VALUES (#name#, #email#, #city#)
  </insert>

  <update id="updateCustomer" parameterClass="com.example.app.domain.Customer">
    UPDATE customers SET city = #city# WHERE id = #id#
  </update>

  <delete id="deleteCustomer" parameterClass="long">
    DELETE FROM customers WHERE id = #id#
  </delete>

</sqlMap>

Positional and Named Parameters

iBATIS uses the #property# syntax inside SQL. The framework reads the value from the parameter object (here a Customer) and binds it safely - the ancestor of MyBatis' #{ }.

Key Points

• Mapping files hold select, insert, update and delete statements.
• #property# safely binds values from the parameter object.
• resultMap with column-to-property mapping shapes the objects.
• A namespace prefixes statement ids (Customer.getCustomer).