Question

我正在使用MySQL和Java，试图制作shoppingcartDB，而我正在尝试删除已经过了30天的元组。

但是编译器说：

线程“main”中的异常java.sql.SQLException：ResultSet关闭后不允许操作

我该如何解决这个问题？

代码：

public static void checkBasketdate() throws Exception {
    //Connect to MySQL:
    Connection con = makeConnection();
    Statement stmt = con.createStatement();
    ResultSet rs1 = stmt.executeQuery("SELECT * FROM basket ;");
    while (rs1.next()) {
        Date Odate = rs1.getDate("orderdate");
        long diff = datediffOfDate(Odate);
        System.out.println(Odate);
        if (diff > 30) {
            //This is where the Exception is thrown:
            stmt.executeUpdate("DELETE FROM basket WHERE orderdate = '" + Odate + "';");
            System.out.println("=>orderdate has been passed 30 days, so delete it");
        }
    }
}

抛出异常的代码行是：

stmt.executeUpdate（“DELETE FROM basket WHERE orderdate ='”+ Odate +“';”）;

Answer 1

你可以在一个时刻执行一个语句，最好的选择是关闭（stmt.close()）第一个语句并运行第二个语句

Answer 2

您可以简单地使用两个语句，第一个用于选择记录，第二个用于删除所需的记录

public static void checkBasketdate() throws Exception {
    //Connect to MySQL:
    Connection con = makeConnection();
    Statement stmt = con.createStatement();
    Statement stmtDelete = con.createStatement();
    ResultSet rs1 = stmt.executeQuery("SELECT * FROM basket ;");
    while (rs1.next()) {
        Date Odate = rs1.getDate("orderdate");
        long diff = datediffOfDate(Odate);
        System.out.println(Odate);
        if (diff > 30) {
            //This is where the Exception is thrown:
            stmtDelete.executeUpdate("DELETE FROM basket WHERE orderdate = '" + Odate + "';");
            System.out.println("=>orderdate has been passed 30 days, so delete it");
        }
    }
    stmnt.close();
    stmntDelete.close();
}

SQLException：ResultSet关闭后不允许操作

2 个答案: