多表联合查询resultType的返回值
一般数据按参数类型返回
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<select id="queryCarIdList" resultType="long"> select id from t_car_car </select> |
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<select id="queryDept" resultType="string"> SELECT deptname FROM t_car_run where deptid = #{deptid} GROUP BY deptname </select> |
根据某字段查询
返回的类型是实体类，因为查询结果数据均为实体类中字段的数据
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<select id="queryNumber" resultType="io.renren.modules.generator.entity.TCarRunEntity"> select number from t_car_car where id = #{carid} </select> |
查询结果为多条记录，存放在list中返回
返回的类型是实体类，因为查询结果数据均为实体类中字段的数据
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<select id="queryCar" resultType="io.renren.modules.generator.entity.TCarCarEntity"> select * from t_car_car </select> |
多表联合查询
- t_car_car
- t_car_driver
- t_car_cardriver
t_car_cardriver存放的两个字段分别是t_car_car和t_car_driver的主键id
解决方案
1.resultType的返回类型是java.util.Map
返回得到的是List中存放的所有数据
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<select id="queryDriver" resultType="java.util.Map"> select driverid from t_car_cardriver where carid = #{id} </select> |
2.新建一个实体类
里面存放的是查询结果里需要的字段名
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// TCarCarDriver private Long carid; private Long driverid; |
返回类型为该实体类
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<select id="queryDriver" resultType="TCarCarDriver"> select driverid from t_car_cardriver where carid = #{id} </select> |
多表联查,返回结果嵌套list
多层集合嵌套返回结果用resultMap,collection中再次使用resultMap
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<resultMap id="chainVo" type="com.suncnpap.intelligentqa.vo.ChainVo"> <id column="cid" property="id"/> <result column="access_key" property="accessKey"/> <result column="secret_key" property="secretKey"/> <result column="outer_chain_name" property="outerChainName"/> <result column="outer_chain_document" property="outerChainDocument"/> <collection property="intentionVos" ofType="com.suncnpap.intelligentqa.vo.ChainIntentionVo" resultMap="intentionVos"/> </resultMap>
<resultMap id="intentionVos" type="com.suncnpap.intelligentqa.vo.ChainIntentionVo"> <id column="iid" property="id"/> <result column="intention_name" property="intentionName"/> <collection property="questionVoList" ofType="com.suncnpap.intelligentqa.vo.MultiQuestionVo"> <id column="qid" property="id"/> <result column="question" property="question"/> </collection> <collection property="wordVos" ofType="com.suncnpap.intelligentqa.vo.ChainIntentionWordVo"> <id column="wid" property="id"/> <result column="word_slot" property="wordSlot"/> <result column="word_slot_miss_question" property="wordSlotMissQuestion"/> <result column="entity_type_ids" property="entityTypeIds"/> </collection> </resultMap>
<select id="detail" resultMap="chainVo"> select tc.id as tid, tci.id as iid, tciw.id as wid, tmq.id as qid, access_key, secret_key, outer_chain_name, outer_chain_document, intention_name, question, word_slot, word_slot_miss_question, entity_type_ids from t_chain tc left join t_chain_intention tci on tc.id = tci.chain_id left join t_chain_intention_word tciw on tci.id = tciw.intention_id left join t_multi_question tmq on tci.id = tmq.parent_id where tc.id = #{id} and tc.deleted = 0 </select> |
