java - 从结果集中更新数据库

Question

SQL 语句层返回多个值，我想用所有这些值更新 db 中的一列这里有什么问题？

        String cust_code = session.getAttribute("Cust_Code").toString();
        String video_typ = session.getAttribute("video_typ").toString();
        int personal_p = Integer.parseInt(session.getAttribute("personal_p").toString());
        int layers_p = Integer.parseInt(session.getAttribute("layers_p").toString());
        String parent_cod = session.getAttribute("parent_code").toString();
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ontube", "root", "123456");
        Statement st = con.createStatement();
        String personal_po = "update customers set personal_p =personal_p + '"+personal_p+"' where membership_num='"+cust_code+"'  ";
        String first_layer="update customers set layers_p = layers_p+'"+layers_p+"' where membership_num='"+parent_cod+"'";
        int pers_points = st.executeUpdate(personal_po);
        int first_lyr = st.executeUpdate(first_layer);
        String layers="select membership_num from customers where parent_num='"+parent_cod+"'" ;
        // i want to update all values comes from these resultset
        ResultSet rs = st.executeQuery(layers);

        while(rs.next()){
       String names =rs.getString(1);

       String update_layers = "update customers set layers_p = layers_p + '"+layers_p+"' where membership_num='"+names+"'  ";

       int  nms = st.executeUpdate(update_layers);

Answer 1

String update_layers = "update customers set layers_p = layers_p + '" + layers_p + "' where membership_num='" + names + "'  ";

应该：

String update_layers = "update customers set layers_p = '" + layers_p + "' where membership_num='" + names + "'  ";

Answer 2

您应该更改这些行：

String personal_po = "update customers set personal_p =personal_p + '"+personal_p+"' where membership_num='"+cust_code+"'  ";
String first_layer="update customers set layers_p = layers_p+'"+layers_p+"' where membership_num='"+parent_cod+"'";
String update_layers = "update customers set layers_p = layers_p + '"+layers_p+"' where membership_num='"+names+"'  ";

替换：
...set xxxxx_p = xxxxx_p + '" + xxxxx_p + "'...用
...set xxxxx_p = '" + xxxxx_p + "'....

更新：
另外，在阅读时不要使用相同Statement的更新ResultSet。

...
Statement st2 = con.createStatement();
while(rs.next()){
    ...
    int  nms = st2.executeUpdate(update_layers);
}
...