I have a table with 50 columns of identifying information that is inconsistently filled out, even for the same individual. Sadly, individuals do not have a unique identifier in this system.
For example, some times we may capture a person's middle name, preferred name, and sometimes it is null - for the SAME individual.
Simplest solution I could think of would be a custom compare function that takes (NULL,VALUE) and returns true, but I'm not sure how to implement this, or if it's even wise.
Ideally I would like to link up records with a lag over partition, but there is frustratingly little information on how partition works other than it takes a 'value expression'. I have tested that it can accept multiple comma separated columns, but the occurrence of null values causes us to miss matches.