Expression help

[Book Man]

HI there, I currently have a database which records book
Loans.

I am creating a Loan query which currently has the
fields:

Student Name
Book Number
Loan Date
Loan Due
Loan Returned
Days Late
Fine Amount

What expression or form of validation could I use to show
only books available and stop anyone taking out a book
which is out on loan.

and

What expression could I use to prevent a book from being
renewed more than twice by the same student.

I do not have a renewed field I would like to add it to
my Loan query with the others I just need an expression
to do so.

if this helps my table relationships are:

STUDENT LOAN INSTANCE BOOK

Student Name Student Name Book Number ISBN
Age Book Number ISBN Author
Class Loan Date Instance Number Genre
Loan Due Department
Loan Returned Age Group
Fine Publisher
Book Title



Thanks

 

[Kevin]

Create an expression in your Query in a new column. Expr1:
IsNull([Loan Returned])

set your Criteria for Expr1 to = False

Only books with a Loan Returned value would show up.
These books should be available

Kevin