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mybatis中使用in查询时的注意事项

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1. 当查询的参数只有一个时
  findByIds(List<Long> ids)
1.a 如果参数的类型是List, 则在使用时,collection属性要必须指定为 list
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<select id="findByIdsMap" resultMap="BaseResultMap">
         Select
         <include refid="Base_Column_List" />
         from jria where ID in
                  <foreach item="item" index="index" collection="list"
                         open="(" separator="," close=")">
                        #{item}
                </foreach>
  </select>
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findByIds(Long[] ids)
1.b 如果参数的类型是Array,则在使用时,collection属性要必须指定为 array
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  <select id="findByIdsMap" resultMap="BaseResultMap">
                 select
                 <include refid="Base_Column_List" />
          from jria where ID in
                  <foreach item="item" index="index" collection="array"
                         open="(" separator="," close=")">
                        #{item}
                </foreach>
  </select>
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2. 当查询的参数有多个时,例如 findByIds(String name, Long[] ids)
这种情况需要特别注意,在传参数时,一定要改用Map方式, 这样在collection属性可以指定名称
         下面是一个示例
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         Map<String, Object> params = new HashMap<String, Object>(2);
        params.put("name", name);
         params.put("ids", ids);
        mapper.findByIdsMap(params);

<select id="findByIdsMap" resultMap="BaseResultMap">
                 select
                 <include refid="Base_Column_List" />
          from jria where ID in
                  <foreach item="item" index="index" collection="ids"
                         open="(" separator="," close=")">
                        #{item}
                </foreach>
   </select>
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完整的示例如下:
例如有一个查询功能,Mapper接口文件定义如下方法:
List<Jria> findByIds(Long... ids);
使用 in 查询的sql拼装方法如下:
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<select id="findbyIds" resultMap="BaseResultMap">
                 select
                 <include refid="Base_Column_List" />
          from jria where ID in
                  <foreach item="item" index="index" collection="array"
                         open="(" separator="," close=")">
                        #{item}
                </foreach>
  </select>
复制代码
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