Mybatis子查询使用

查询一年内的达标天数

  <select id="getAllDistrictDayAqis" resultMap="AirDayReportMap">
        SELECT
            district_code as "districtCode",
            aqi,
            aqi_grade as "aqiGrade",
            primary_pollutant as "primaryPollutant",
            report_time as "reportTime",
            pm2_5 as "pm2_5",
            o3 as "o3",
            no2 as "no2",
            so2 as "so2",
            pm10 as "pm10",
            co as "co",
            time,
        (select count(1) from aqi_district_day d where d.district_code = main.district_code and d.aqi_grade &lt; 2 and d.time >= #{firstDayOfYear} and d.time &lt;= #{day}) as good_days
        FROM aqi_district_day main
        WHERE time = #{day}
    </select>

这里的亮点是where d.district_code = main.district_code 控制数据是当前行政区的数据，不会多