Example: orders.4gl (Function item_delete)

This function implements the SQL row deletion for an order item row.

Function item_delete (orders.4gl):

  1 PRIVATE FUNCTION item_delete(x INTEGER) RETURNS BOOLEAN
  2 
  3   TRY
  4      DELETE FROM items
  5         WHERE items.stock_num = orditems[x].stock_num
  6           AND items.order_num = order_rec.order_num
  7   CATCH
  8      CALL comutils.mbox_ok(title2,SQLERRMESSAGE)
  9      RETURN FALSE
 10   END TRY
 11 
 12   MESSAGE msg10
 13   CALL comp_order_total()
 14   RETURN TRUE
 15 
 16 END FUNCTION

Note:

Line 1 declares the function with the x integer parameter representing the index in the orditems array, and returns a boolean to indicate if the SQL command succeeds.
Lines 3 thru 10 implement the SQL DELETE command, to remove the row from the items table that has the stock_num equal to the current order item of the list (orditems[x].stock_num), and the order number equal to the current order number (order_rec.order_num)
Lines 8 and 9 are executed when an SQL error occurs, and returns from the function with FALSE.
Line 12 shows a message to the user to indicate that the SQL operation succeeded.
Line 13 re-computes the order total by calling the comp_order_total function.
Line 14 returns TRUE to the caller.