VALIDATE ROUTINE FOR CHEQUE-ID

HI,
DOUBT1 : i have one doubt,in ID Routine i need to Check wheither the given cheque number is Valid or Not, is there any way Without SELECT a Table.

DOUBT2 : i have one doubt,in ID Routine i need to default Cheque Number from @ID(Cheque Number)...(If i enter valid cheque id then cheque number should be auto popup, if i enter invalid cheque id then i should get a ERROR MESSAGE...)
this is the problem...can u give any suggestions regarding tihs..

TAB1---> SHOULD BE VALID CHEQUE-ID OTHER WISE it should through ERROR MESSAGE Immediately without opening a new tab
TAB2---> IF it is valid ID Then CHEQUE NUMBER Field Should be Auto popup..

1. I know no file where the cheque number (talking about CHEQUE.ISSUE, CHEQUE.REGISTER, CHEQUE.REGISTER.SUPPLEMENT) itself is the key so that you can use READ.
Without account and type of cheque you can only do a SELECT. Alternatively you can build your own file when you issue cheques.

2. In CHECK.ID.RTN set variable E to your error message, this should stop further processing. To populate the field just move ID.NEW to the position in R.NEW(xxx).