Question

好的，我正在尝试使用JDBC打印SUM和AVG函数的结果。所以基本上，它不起作用。我做错了什么？

   <table border="1">
     <tr><th>Total Homes Sold</th><th>Total Sales Amount</th><th>Averages Price Per Home</th></tr>    

       <% rset = stmt.executeQuery("SELECT COUNT(home_ID) FROM home");%>
       <% rset1 = stmt.executeQuery("SELECT SUM(purchase_Price) FROM home");%>          
       <% rset2 = stmt.executeQuery("SELECT AVG(purchase_Price) FROM home");%>

       <tr>
         <td><%= rset.getString(1) %></td>
         <td><%= rset1.getString(1) %></td>
         <td><%= rset2.getString(1) %></td>
      </tr>

   </table>

Answer 1

主要问题是你需要在结果集上调用 next（）（在 executeQuery（）之后）来检索结果集的第一行（甚至虽然只有一行）。

你没有这样做，没有行可用，并且调用 getString（）导致＆＃34; ResultSet关闭＆＃34;错误。

Answer 2

尝试做：

   <tr>
   <% rset = stmt.executeQuery("SELECT COUNT(home_ID) FROM home");%>
     <td><%= rset.getString(1) %></td>
   <% rset = stmt.executeQuery("SELECT SUM(purchase_Price) FROM home");%>          
     <td><%= rset.getString(1) %></td>
   <% rset = stmt.executeQuery("SELECT AVG(purchase_Price) FROM home");%>
     <td><%= rset.getString(1) %></td>
  </tr>

或更好：

   <tr>
   <% rset = stmt.executeQuery("SELECT COUNT(home_ID), SUM(purchase_Price), AVG(purchase_Price) FROM home");%>
     <td><%= rset.getString(1) %></td>
     <td><%= rset.getString(2) %></td>
     <td><%= rset.getString(3) %></td>
  </tr>

如何使用JDBC打印SUM和AVG SQL值？

2 个答案: