i want to create auto increment id using preparedstatement, i'm using oracle database and this is my code
public Client newClient(Client client){
try {
con = DBConnection.getConnection(driver, url, name, pass);
pstmt = con.prepareStatement("INSERT INTO CLIENT (FIRSTNAME, LASTNAME, CAREER, CSALARY) VALUES (?, ?, ?, ?)", Statement.RETURN_GENERATED_KEYS);
pstmt.setString(1, client.getFirstName());
pstmt.setString(2, client.getLastName());
pstmt.setString(3, client.getCareer());
pstmt.setInt(4, client.getcSalary());
pstmt.executeUpdate();
rs = pstmt.getGeneratedKeys();
rs.next();
int id = rs.getInt(1);
client.setcId(id);
}catch(Exception ex){
ex.printStackTrace();
return null;
}finally{
try{ rs.close(); }catch (Exception e){}
try{ pstmt.close();}catch (Exception e){}
try{ con.close();}catch (Exception e){}
}//finally
return client;
}`
but i have this error
java.sql.SQLException: ORA-01400: cannot insert NULL into ("AHMAD"."CLIENT"."CID")
plz help me