Question

我正在尝试使用SQLite创建JDBC医生，但是当我调用Delete和Update方法时，我收到以下错误消息：

线程“main”java.sql.SQLException中的异常：Doctor not deleted

[SQLITE_BUSY]数据库文件已锁定（数据库已锁定）

这些是DoctorDAO类中的主要类和两种方法。

    public static void main(String[] args) throws SQLException, IOException {
        scanner = new Scanner(System.in);
        sc = new Scanner(System.in);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        DoctorDAO a = new DoctorDAO() ;

        Doctor d1 = new Doctor(null,null,null,(char) 0,null,null,null,null,null,null);
                    boolean ins = a.insertEmployee(d1);
                    if(ins){System.out.println("has added");}
                    else{System.out.println("not added");}


       System.out.println("Give Doctor's Id");
                    String id1 = sc.nextLine();
                    a.updateDoctrorByIds(id1);
         }


   public boolean updateDoctrorByIds(String Id) throws SQLException, IOException
   {  
 boolean b = true; 



       try
       {
           getConnection();
           c.setAutoCommit(false);

         // create the java mysql update preparedstatement 
         Scanner sca = new Scanner(System.in);
         System.out.println("Give the new Name");
         String newName = sca.nextLine();
         String query = "update doctors set Name = ? where Id = ?";
         PreparedStatement preparedStmt = c.prepareStatement(query);
         preparedStmt.setString(1,Id);
         preparedStmt.setString (2,newName);

         // execute the java preparedstatement
         preparedStmt.executeUpdate();
         c.commit();


               closeConnection();

       } 
       catch (Exception e)
       { b =false ;
         System.err.println("Got an exception! ");
         System.err.println(e.getMessage());

       }
   return b;  
   }

public boolean deleteDoctrorById(String Id) throws SQLException` {

       boolean b = true;

       try {

            getConnection();
            c.setAutoCommit(false);
            System.out.println("Delete operation");

            String query = "DELETE FROM doctors WHERE ID ='"+Id+"';";
            s = c.createStatement();
            s.executeUpdate(query);
            //System.out.println(res);

            c.commit();
            s.close();
            c.close();


               //closeConnection();
               System.out.println("/");
               System.out.println("/");
               System.out.println("Successfully Deleted");
               System.out.println("/");
               System.out.println("/");

       }
       catch (SQLException s){
            b = false;
           throw new SQLException("Doctor not deleted"); }


    return b;

   }

Answer 1

我可以在您的代码中看到一个明显的错误 - 对于Update，您说的是

String query = "update doctors set Name = ? where Id = ?";

然后你正在做，

preparedStmt.setString(1,Id);
preparedStmt.setString (2,newName);

这是相反的顺序。根据您的查询，名称是第一个参数， id 是第二个参数，但您反向设置值。

由于您粘贴的代码不是正常工作的代码，因此无法为数据库锁定错误提示多少但要避免 数据库已锁定错误，建议关闭连接，即使您获得Exception，请尝试关闭finally块内的连接。

JDBC删除和更新方法

1 个答案: