Is there a Get (LastError )=401 for related record

[cclub75]

Hi,

In search mode, when no records are found, we can use the Get ( LastError )=401.

But within a relationship with the Go To Related Records script?

How can I know that no record is related ?

It's weird, because if the user clicks on a button with the Go To Related records script, and that no record is shown, then nothing happen.

Chris

[Fenton]

One great advantage of relationships is that you can check BEFORE you use them. First, you need a field that you're sure has data in it in the related table; or at least would have data for that relationship, such as the right hand key of the relationship.

If [ not IsEmpty(relationship::field) ]

Go To Related Record ["relationship"]

Else

Do whatever if no match

End If

[cclub75]

Thanks Fenton for your interesting idea. But in this case, I've forgotten to specify that it is a self joined relationship and a ">" type. The right hand key is thus always filled.

By the way, maybe I can explain why I use this scheme : I'm reluctant to use the perform find function, because I think relationships are faster. But it may be a false idea. What do you think ?

[Fenton]

It doesn't make any difference. If there's none greater, the related field is empty, when you try to access it via the relationship. Try it. Yes, relationships are faster.

[cclub75]

Ah... I found something.

Just use the ErrorCode 101 ("record is missing").

set Error Capture (On)

Go to related record

if (Get(LastError)=101)

beep : "not found"

end if

[-Queue-]

No need to go to a related record when none exist. It's easier to do as Fenton wrote,

If [not IsEmpty(relationship::serial)]

Go to Related Record [show only related; relationship]

Else

Show Custom Dialog ["No related records exist."]

End If

If there are one or more related records, then relationship::serial (the right-hand key) will not be empty.

[Vaughan]

I use Count (relationship::keyfield ) > 0, but it has been suggested that this is slower.

[-Queue-]

Yes, if there are multiple related records, then Count would be slower. IsEmpty only checks the first related field and doesn't have to count anything, just return a boolean. I assume it would only need to test whether Left( field; 1 ) is empty. But I'm not sure if it does test the entire field. Either way, it would theoretically be faster.