使用sql确定数据集的变化率

如果您的表被称为带有日期，项目和值整数列的数据表，则可能会这样做

SELECt t1.day, t1.item, (t2.value - t1.value) as rateFROM datatable t1INNER JOIN datatable t2ON t1.item = t2.item AND t1.day + 1 = t2.day