我在项目中将MyBatis用于持久层。
我在mySql db中有两个表，paytransaction和paymenttype，定义如下：
PayTransaction PaymentType
Field Field
------------- -------
id
payment_state
creation_date
update_date
payment_type ----FK---->id
payment_id description
因此，paytransaction通过payment_type列（外键）关联了一个付款类型。
我的映射器的定义如下：
PayTransaction
<resultMap id="payTransactionPaymentTypeResultMap" type="com.XXX.payplatform.model.to.impl.TOPayTransaction" >
<id column="id" property="id" javaType="long"/>
<result column="payment_state" property="payment_state" javaType="string"/>
<result column="creation_date" property="creation_date" javaType="date"/>
<result column="update_date" property="update_date" javaType="date"/>
<result column="payment_id" property="payment_id" javaType="long"/>
<association column="payment_type" property="paymentType" javaType="com.XXX.payplatform.model.to.impl.TOPaymentType" resultMap="com.XXX.payplatform.model.dao.interfaces.IDAOPaymentType.paymentTypeResultMap"/>
</resultMap>
付款方式
<resultMap id="paymentTypeResultMap" type="com.XXX.payplatform.model.to.impl.TOPaymentType" >
<id column="id" property="id" javaType="long"/>
<result column="description" property="description" javaType="string"/>
</resultMap>
SQL JOIN语句是：
<sql id="joinPayTransactionPaymentType">
select paytransaction.id, paytransaction.payment_state, paytransaction.creation_date,paytransaction.update_date, paytransaction.payment_id,
paymenttype.id, paymenttype.description
from paytransaction
INNER JOIN paymenttype ON paymenttype.id = paytransaction.payment_type
</sql>
该问题与paytransaction和Paymenttype表中名为“ id”的列有关。映射对象时，ID字段具有相同的值，即，如果paytransaction的ID为39，则映射后的Java对象中paytype的ID在db中为3时也将为39。
我试过写别名，例如：
<sql id="joinPayTransactionPaymentType">
select paytransaction.id AS "paytransaction.id", paytransaction.payment_state as payment_state, paytransaction.creation_date as creation_date,paytransaction.update_date as update_date, paytransaction.payment_id as payment_id,
paymenttype.id AS "paymenttype.id", paymenttype.description as description
from paytransaction
INNER JOIN paymenttype ON paymenttype.id = paytransaction.payment_type
</sql>
但是没有结果。我认为唯一可行的解决方案是更改db中列的名称，例如“ paymenttype_id”和“ paytransaction_id”。
有什么解决方案，或者这是mybatis错误？
谢谢！
最佳答案
只要您能够将确定的列（或列别名）映射到这些属性，对于MyBatis来说，拥有相同的属性名称就不是问题。为结果列指定别名时，也应为paymentTypeResultMap指定相同的列名。那应该可以了。
<resultMap id="payTransactionPaymentTypeResultMap" type="com.XXX.payplatform.model.to.impl.TOPayTransaction" >
<id column="id" property="id" javaType="long"/>
<result column="payment_state" property="payment_state" javaType="string"/>
<result column="creation_date" property="creation_date" javaType="date"/>
<result column="update_date" property="update_date" javaType="date"/>
<result column="payment_id" property="payment_id" javaType="long"/>
<association column="payment_type" property="paymentType" javaType="com.XXX.payplatform.model.to.impl.TOPaymentType" resultMap="com.XXX.payplatform.model.dao.interfaces.IDAOPaymentType.paymentTypeResultMap"/>
</resultMap>
...
<resultMap id="paymentTypeResultMap" type="com.XXX.payplatform.model.to.impl.TOPaymentType" >
<id column="paymenttype_id" property="id" javaType="long"/>
<result column="description" property="description" javaType="string"/>
</resultMap>
...
<sql id="joinPayTransactionPaymentType">
select paytransaction.id, paytransaction.payment_state as payment_state, paytransaction.creation_date as creation_date,paytransaction.update_date as update_date, paytransaction.payment_id as payment_id,
paymenttype.id AS paymenttype_id, paymenttype.description as description
from paytransaction
INNER JOIN paymenttype ON paymenttype.id = paytransaction.payment_type
</sql>