@Brownfox:
Yes there are different and more sophisticated methods to create a database application.
All of them have their justification and purpose, depending on the size of the project, its use, and the programmer's experience.
You described yourself as a beginner, so I'll show you how to solve your problem using Lazarus's built-in tools.
You don't have to deal with parameters at all, because Lazarus's database components do that for you.
In the small test application, you will see a simple mask in the fcustomer.pas form.
The form only contains a grid, several data-sensitive input fields, and a DBNavigator that takes control.
The database components determine how to handle the assigned SQL statement.
Of course, you can make everything more beautiful and complex, but this should be enough for a first understanding.