In Information Analyzer one can implement a reference check against only a single column using in_reference_column. But in many cases you need to check references against a set of columns. E.g. imagine you need to implement a simple address check using city and postal code. If you have a reference table that contains all valid combinations of postal codes and cities (postCode, city). Currently you cannot implement this directly with a in_reference_column check as you can either check against the postCode or the city, but not the combination of it. Imagine you had a in_reference_table check where you code specify multiple columns like this:
(sourceCity, sourcePostCode) in_reference_table (refPostCode, refCity)
Currently without this function you need to create a view over the reference table that merges the 2 columns into a single column and you need to concatenate the source columns. This is significant effort to implement and it looks ugly.
Generally it would be nice if a variable in a data rule can be bound to an n-tuple instead of a single column / field. This would allow a much greater flexibility and reuse. E.g. imagine you a data rule definition:
Currently this can only be bound to a single field like e.g. CreditCardNo. But it cannot be bound to CreditCardNo and CreditCardExpirationDate at the same time. To verify credit card information exists you would need to write instead:
A Exists and B Exists
If you could bind (CreditCardNo, CreditCardExpirationDate) to a single variable you dont need this, but you can stick to a simple A Exists data rule definition, increasing the re-use of data rule definitions significantly. The bound rule would look like this then:
(CreditCardNo, CreditCardExpirationDate) Exists
With it you also do not need an additional in_reference_table check, but you could stick to the in_reference_column check.
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