Deleting an existing user from a database JDBC Oracle

Question

I have a working code here that removes users from a database when you call the removeUser method. :

public void removeUser(String username)
    {

        try {
            pstmnt = conn.prepareStatement("DELETE FROM user_info WHERE username = ?");
            pstmnt.setString(1, username);
            pstmnt.executeUpdate();

            pstmnt = conn.prepareStatement("DELETE FROM users WHERE username = ?");
            pstmnt.setString(1, username);
            pstmnt.executeUpdate();



            //pstmnt.executeBatch();
            System.out.println("Removed User :" + username);
        } catch (SQLException e) {System.out.println("Error: " + e.getMessage()); }
    }

However, I need to make sure the user exists before I delete him, otherwise print that the user does not exist. How can this be accomplished?

Answer 1

You could instead use the result of pstmnt.executeUpdate() to determine if the SQL DELETE operation was successful:

int rowsUpdated = pstmnt.executeUpdate();
if (rowsUpdated == 0) {
    System.out.println("User does not exist");
} else {
    System.out.println("User deleted");
}

Answer 2

pstmnt.executeUpdate() returns row count. which says how many rows are deleted!!

Thus if it's value zero then show message user does not exist. .

Answer 3

Calling executeUpdate will return the number of rows that were modified by the call. Do something like this:

          pstmnt = conn.prepareStatement("DELETE FROM users WHERE username = ?");
          pstmnt.setString(1, username);
          int rows = pstmnt.executeUpdate();
          if (rows == 0) {  
              //record does not exist 
              System.out.println("User does not exist");
          } else if (rows > 0) {  
              //there were # of rows deleted
              System.out.println(rows + " User records deleted");

          }