>>Adding my voice to the chorus, be cautious with nulls. They have their place but it's very easy to run into unintended / unanticipated side effects. I worked for three years supporting a large VFP app which was originally written by a guy who was in love with nulls. Our main support person estimated that half our customer support issues were eventually traced back to problems with NULL.
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>We had one last that in the last week. I estimate that 6 to 8% of the known issues were related to NULLs in the database. Once we fully implemented the framework and normalized the data, we almost brought it down to 0%. The one of last week was caused by a robot which will go off production in a few days. So, it wasn't updated (old code out of the framework) to avoid NULLs.
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>I also avoid NULLs in the SQL command when using LEFT JOINs. When I build the SQL command, I call a method loData.IsNull(), which will make sure to avoid receiving NULL values in the result and put empty values instead.

Bases on your and Sergey's input I will have to go through all my SQL server tables and make sure I have an empty string as default on those columns that may affect my program. Not a trivial task since the app has about 90+ tables.