java - 为什么在尝试对 ResultSet 中检索到的列的值求和时出现错误？

Question

我的代码有什么问题？我认为它在 SQL 中，但我不知道为什么。提前谢谢你

try{
    clsConnect c = new clsConnect();
    Connection conn = c.makeConnection();
    Statement statement = conn.createStatement();
    String display = "SELECT SUM(Amountpaid) from mofficetbl";
    ResultSet rs = statement.executeQuery(display);
    while(rs.next()){
        totalTF.setText(rs.getString("Amountpaid"));
    }
}
catch (SQLException e) {
    JOptionPane.showMessageDialog(null, e);
}

Answer 1

当你调用这个select语句时；返回的列实际上称为“SUM(amountpaid)”而不是 amountpaid 因此要么将其别名更改为

"SELECT SUM(Amountpaid) as Amountpaid from mofficetbl"

您还可以:

rs.getString("Sum(Amountpaid)");