Hello Charlie,
You can get ItemID of the newly created item of the custom table just by accessing
ItemID property. If you have already looked at API example in
Developer's Guide, it could look like this for the example mentioned there:
// Creates new custom table item
CustomTableItem newCustomTableItem = CustomTableItem.New(customTableClassName, customTableProvider);
// Sets the ItemText field value
newCustomTableItem.SetValue("ItemText", "New text");
// Inserts the custom table item into database
newCustomTableItem.Insert();
TextBoxItemID.Text = "ItemID: " + newCustomTableItem.ItemID.ToString();
Best regards,
Filip Ligac