How to compare dates from two tables with blanks values - Mailing list pgsql-general

From Mike Martin
Subject How to compare dates from two tables with blanks values
Date
Msg-id CAOwYNKZqi9L4mT3B1FEAQEoT47NLuGJtyR5ZB58nFFDBseUpLQ@mail.gmail.com
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Responses Re: How to compare dates from two tables with blanks values  ("Arnaud L." <arnaud.listes@codata.eu>)
List pgsql-general
I have a situation where I need to update dates in a primary table from regular imports of data, eg: this is the base select query

select d.row_id, fname||lname,'joineddate',d.joineddate,'joineddate',s.joineddate,0 as bool1 from import s join  members d on d.contact_id=s.contact_id where

cast(nullif(d.joineddate,NULL) as timestamp) != cast(nullif(s.joineddate,'') as timestamp)

This gives zero records, however I cant seem to get a query that works.
For non-date fields I just use Coalesce(fieldprime,'')!=coalesce(fieldiimport,'') which works fine but chokes on dates where there is a blank value

thanks in advance

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