mybatis遇到的问题

    <select id="testSql" resultType="java.lang.Integer">
        select
            case month(o.create_time) when '1' then count(*) else 0 end as 1月,
            case month(o.create_time) when '2' then count(*) else 0 end as 2月,
            case month(o.create_time) when '3' then count(*) else 0 end as 3月,
            case month(o.create_time) when '4' then count(*) else 0 end as 4月,
            case month(o.create_time) when '5' then count(*) else 0 end as 5月,
            case month(o.create_time) when '6' then count(*) else 0 end as 6月,
            case month(o.create_time) when '7' then count(*) else 0 end as 7月,
            case month(o.create_time) when '8' then count(*) else 0 end as 8月,
            case month(o.create_time) when '9' then count(*) else 0 end as 9月,
            case month(o.create_time) when '10' then count(*) else 0 end as 10月,
            case month(o.create_time) when '11' then count(*) else 0 end as 11月,
            case month(o.create_time) when '12' then count(*) else 0 end as 12月
        from orders o
        where date_format(o.create_time, '%Y') = YEAR (CURDATE())
    </select>

查询到了,但是无法接收

    @Test
    void contextLoads() {
        List<Integer> integers = ordersMapper.testSql();
        System.out.println("===================================================");
        System.out.println(integers.size()); // 1
        System.out.println("===================================================");
    }

resultType="java.lang.Integer"、resultType="int"
resultType="integer" 、resultType="arraylist"、resultType="list" 都没效果

最终还是选择了最笨的循环查询但是效率很低

    <select id="getEveryMonthOrderNum" parameterType="string" resultType="int">
        select case month (o.create_time) when #{m} then count(*) else 0 end 
        from orders o
        where date_format(o.create_time, '%Y') = YEAR (CURDATE())
    </select>

controller

    @ApiOperation(value = "获得一年每月订单数")
    @GetMapping("/getEveryMonthOrderNum")
    public Result getEveryMonthOrderNum() {
        String[] months = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12"};
        List list = new ArrayList<Integer>(12);
        for (String month : months) {
            list.add(ordersService.getEveryMonthOrderNum(month));
        }
        Map<String, Object> map = new HashMap<>(16);
        map.put("everyMonthOrderNumList", list);
        return Result.ok().data(map);
    }

结果

{
  "code": 200,
  "msg": "成功",
  "data": {
    "everyMonthOrderNumList": [
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      14,
      0,
      0
    ]
  }
}