Related Tables

Question

How to I know wether or not a record from a Table is related with others Tables. If the user want to delete a record from a teble and it's related with otrhers records I want to display a warning message otherwise just delete it. What can I do. Thanking in advance. Carlos

meenu_vij04 · Answer

Hi csanchez if u want to create a relation between Customers & Orders Tables  you can do this: parentCol = ds.Tables[Customers].Columns[Customer_ID]; childCol = ds.Tables[Orders].Columns[Customer_ID]; // create a Relation called CustOrder DataRelation dr = new DataRelation(CustOrder parentCol childCol) // add a relation ds.Relations.Add(dr); now datarelation added in your dataset if u want to get a specific row you can use SelectedIndex prop int x = listBox1.SelectedIndex; parentRow = ds.Tables[Customers].Rows[x]; childRow = parentRow.GetChildRows(dr); foreach(DataRow drow in childRow) { Console.WriteLine(drow[Column1]+ +[Column2].ToString()); } then u will get all the related records for that particular row. if u still have questions then u can ask me. bye

Carlos Sanchez · Answer

Somebody knows about DataSet.Relations.Add() and GetChildRows()? How do they work? thanx.

Carlos Sanchez · Answer

What is a trigger? My questions are: For example: I have the next Data Base: *Customers* ---------------- ID_Customer Name Address TelephoneNum *Orders* ------------- ID_Order ID_Cliente Date - I want to create a relationship (Customers.ID_Customer = Orders.ID_Customer). How can I create it? - In my application the user can delete a customer but I want to know wether or not the customer have orders if the costumer have one or more orders I have to display a message: Is not possible delete this Customer. How can I do it? Thanx Carlos

jinwolf · Answer

That's why you have relationships in a database. you can use a trigger.