Key Down Trigger

Question

Plz assist me.
I have a form with a textitem Name and I do not want the user to enter any key apart from [A-Z] i.e ascii value (65 to 90). I want to create a trigger on key-down which returns simple message "plz enter characters only" if user enters any key apart from [A-Z].
Plz answer Thank you.

Answer 1

Create or Replace function funasc (RC Varchar2) Return Boolean
is
vali Number := 0;
kv Number := 0;
vk Number := 0;
as Number := 0;
ab Number := 0;
len Number := 0;
Begin
len := length(RC);
For I in 1..len Loop
If I <> 4 then
vali := ascii(substr(RC, I, 1);
If Vali Between 65 and 90 then
kv := kv + 1;
Else
ab := ab + 1;
End if;
Elsif I = 4 then
vali := ascii(substr(RC, I, 1);
If vali = 45 then
vk := 1;
Else
ab := 1;
End if;
End If;
End Loop;
as := KV + vk;
If as <> len then
Return True;
Elsif as = len then
Return False;
End if;
End;
Trigger : When-Validate-Item
Text_Item : Route_Code
Declare
RC Fare.Route_Code%Type;
Alt Number;
Begin
If funasc(:fare.route_code) then
message ('Route Code : ' || :fare.route_code || ' is invalid.!');
Set_Alert_Property ('ALERTRC', title, 'ROUTE CODE VIOLATION');
Set_Alert_Property ('ALERTRC', alert_message_text, 'Route Code : ' || :fare.route_code || ' is invalid. Plz enter Route Code in [ABC-XYZ] format.!');
Alt := Show_Alert ('ALERTRC');
Raise Form_Trigger_failure;
Else
Select route_code into :fare.route_code from Fare where route_code = :fare.route_code;
message ('Route Code : ' || :fare.route_code || ' already exists.!');
Set_Alert_Property ('ALERTRC', title, 'ROUTE CODE VIOLATION');
     Set_Alert_Property ('ALERTRC', alert_message_text, 'Route Code : ' || :fare.route_code || ' already exists.!');
Alt := Show_Alert ('ALERTRC');
Raise Form_Trigger_failure;
Else
Null;
End if;
End if;
Exception
When No_Data_found Then
     Null;
End;
Wht this coding does is if route_code is not ABC-XYZ format then it through an alert, also if user enters number instead of char then it popup an alert.
Now can this coding be made even smaller.