对数据库中重复主键进行判断

来源：互联网发布：淘宝爆款采集软件编辑：程序博客网时间：2024/05/22 07:53

String sql = "select sub_id from subject";//查询subject表的sub_id
    resultSet = statement.executeQuery(sql);
    int iscount = 0;
    while(resultSet.next()) {
       data[0] = resultSet.getString("sub_id");
       if(this.sub_idTextField.getText().equals(data[0]))
       {   iscount++;   }
    }
    if(iscount == 0){
     if(this.sub_nameTextField.getText().trim().equals(""))
     { JOptionPane.showMessageDialog(this, "科目不能为空！！"); }
     else
      if(addSub_IdNumber(this.sub_idTextField.getText()) == true &&
        addSub_IdNumber(this.creditTextField.getText()) == true){}

JOptionPane.showMessageDialog(this, "增加成功！！");
       this.sub_idTextField.setText("");
    this.sub_nameTextField.setText("");
    this.creditTextField.setText("");

     // }else JOptionPane.showMessageDialog(this, "科目输入格式错误！！");
       }
      else JOptionPane.showMessageDialog(this, "输入科目ID或学分格式错误！！");
    }
    else
     JOptionPane.showMessageDialog(this, "请输入不同的科目ID！！");

public static boolean addSub_IdNumber(String str) { //判断输入是否为正确的科目ID类型 ( 正则式)
  Pattern pattern = Pattern.compile("// *[0-9]*// *");
  Matcher isNum = pattern.matcher(str);
  if (!isNum.matches()) {
   return false;// 输入是字符时的返回值
  }
   return true;// 输入是数字时的返回值
     }