根据MySQL中相似的日期求和列对应的值？
为此，将聚合函数SUM()与GROUPBY一起使用。让我们首先创建一个表-
mysql> create table DemoTable1522 -> ( -> ProductPurchaseDate date, -> NumberOfProduct int -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1522 values('2019-01-21',45);
mysql> insert into DemoTable1522 values('2018-12-31',78);
mysql> insert into DemoTable1522 values('2019-01-21',67);
mysql> insert into DemoTable1522 values('2019-03-01',56);
mysql> insert into DemoTable1522 values('2018-01-21',97);
mysql> insert into DemoTable1522 values('2019-01-21',47);使用select语句显示表中的所有记录-
mysql> select * from DemoTable1522;
这将产生以下输出-
+---------------------+-----------------+ | ProductPurchaseDate | NumberOfProduct | +---------------------+-----------------+ | 2019-01-21 | 45 | | 2018-12-31 | 78 | | 2019-01-21 | 67 | | 2019-03-01 | 56 | | 2018-01-21 | 97 | | 2019-01-21 | 47 | +---------------------+-----------------+ 6 rows in set (0.00 sec)
以下是根据MySQL中的日期对列进行计数的查询-
mysql> select ProductPurchaseDate,sum(NumberOfProduct) from DemoTable1522 -> group by ProductPurchaseDate;
这将产生以下输出-
+---------------------+----------------------+ | ProductPurchaseDate | sum(NumberOfProduct) | +---------------------+----------------------+ | 2019-01-21 | 159 | | 2018-12-31 | 78 | | 2019-03-01 | 56 | | 2018-01-21 | 97 | +---------------------+----------------------+ 4 rows in set (0.00 sec)