How to avoid repeated input in a form

[Jane]

Hello£¬

I have 2 tables, "shop table" and "shop sales table", which connected by "1
to ¡Þ" relation. That is to say, one shop have several sales records in
"shop sales table" . When I input sales records by form, how to set a rule
that avoid the repeated date inputed in one shop?

Thanks.

J.J.

 

[ChrisM]

In message (e-mail address removed),

Hello£¬

I have 2 tables, "shop table" and "shop sales table", which connected
by "1 to ¡Þ" relation. That is to say, one shop have several sales
records in "shop sales table" . When I input sales records by form,
how to set a rule that avoid the repeated date inputed in one shop?

Thanks.

J.J.

What is the shop-sales data that you are entering (could you give an
example?)

....and what would constitute repeated data? (eg I guess it would be possible
for the same shop to sell the same item(different instances of it though) on
the same day more than once and that would still be correct(?)