1.统计本月、上月数据
// 上月
long lastMonth = new DeviceRepairs() .selectCount( Wrappers.lambdaQuery(DeviceRepairs.class) .apply( " PERIOD_DIFF( date_format( now( ), '%Y%m' ), date_format( create_time, '%Y%m' ) ) =1 ") .last(" limit 1"));
// 本月
long currentMonth= new FarmCrop() .selectCount( Wrappers.lambdaQuery(FarmCrop.class) .apply( " DATE_FORMAT( create_time, '%Y%m' ) = DATE_FORMAT( CURDATE( ) ,'%Y%m' ) ") .last(" limit 1"));
2.聚合函数
DeviceWeatherData maxSpeed = new DeviceWeatherData() .selectOne( Wrappers.query(new DeviceWeatherData()) .select(" max(windSpeed) as windSpeed ") .lambda() .eq( DeviceWeatherData::getDeviceId, deviceId) .apply( " to_days(create_time) = to_days(now()) "));