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GROUP BY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)