使用group-by时，在JSP中获取聚合列值。

I have a problem when retrieving data from a SQL using JSP.

在使用JSP从SQL检索数据时，我遇到了一个问题。

ResultSet rs = statement.executeQuery("select orderdate, 
                                              SUM(orderingcost) 
                                         from `shopping`.`order` 
                                     group by orderdate");
int count = 0;
//String

while (rs.next()) {
  //String orderdate = rs.getString("orderdate");
  //String orderingcost = rs.getString("orderingcost");
  System.out.println(count);
  count++;
}

I use group by statement to group some data.

我使用group by语句对一些数据进行分组。

However, I don't know how to get the data out when group by is applied.

然而，当group by应用时，我不知道如何获取数据。

Can anyone help me?

谁能帮我吗?

1 个解决方案

#1

You need to alias the column:

您需要将列别名为:

select orderdate, SUM(orderingcost) orderingcost from `shopping`.`order` group by orderdate

Then you'll have a column named orderingcost in your resultset, and you can do:

然后在resultset中有一个名为orderingcost的列，您可以这样做:

double orderingcost = rs.getFloat("orderingcost") // probably need getFloat instead of string since it's a numeric value

#1