Syntax to trigger removal of a link between between tables
Greetings: I am trying to break a link between two tables, triggered when certain conditions are met. what is the correct syntax to break a link?
I have two tables, Trips and Locales, and a third table, Visits, which records Trips to the Locale.
Trips : Locales = 1 : n (non-composition).
Locales : Visits = 1 : n (composition).
In Visits, table Trigger-onCreate field, I use this code, which does not work.
let myTrip := TripID;
let myLocale := LocaleID;
let b := last(select Locales where number(Id) = myLocale and number(trips.Id) = myTrip);
b.number(Id := null)
Thanks for your help.
3 replies
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Hi Laura,
the formula to break a link:
---
'Linked field':=0
---
I do not understand your formula. What do you want to achieve with it?
Leo
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Perfect! Thank you.
I’ll try to get back to you a bit later with more details on what I’m working on.
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Hi, Leonid, if you mean what were those additional lines of code for, I can see why you were baffled! None of the earlier lines were needed—they were only there because I was flailing around, trying to get something to work when my original line of code:
'Linked field' := null
didn't.
This may be more than you were asking for, but if you mean more broadly what am I trying to achieve with this system, I am building a database that enables business travelers in our small business to select a particular locale, and log their business travel dates there.
If you live in the US, I'm sure you already know this; business travelers here can use a government-approved per diem rate for business deductions, in lieu of having to keep track of all their travel receipts. To do this, I have a table Trips that stores some info about travel; and Locales, a table of potential travel destinations. Locales has two subtables: Per Diems, which houses IRS-approved per diem rates by year for each city; and Visits, a subtable that keeps track of the dates that the traveler visited that particular locale on business.
I use a 1:∞ link, non-composition, between Trips and Locales, and a button that allows the user to input dates and use the link search mechanism to select or add their travel destination(s) and dates. At that point, Visits ( ∞:1 with Trips) is visible to the user from the Trips log form, and has a list of the places they've been during that trip, plus their deductible amounts spent versus per diem rates.
I break the link between Trips and Locales after each Visits entry, to enable the locale to be used as a destination for a different trip.
-l.
Content aside
- 6 yrs agoLast active
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