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使用group by统计各个类型下的数量:
<select id="countNums" resultMap="BaseResultMap" >
select count(id) num,state id from user group by state
</select>
<resultMap id="BaseResultMap" type="Map">
<result column="state" property="state" jdbcType="INTEGER" />
<result column="num" property="num" jdbcType="INTEGER" />
</resultMap>
如果有对应的实体类,则可以把resultMap值换成实体类