Update all SQL NULL values in multiple columns using Column level WHERE clause?

Question

We have a database with a bunch of wide tables (40-80 columns each) and just found a bug that introduced NULL values into about 500 of the records. The NULL values can appea

Answer 1

I don't like the idea to manipulate the data itself for the purpose of reporting. If you change the NULL values to 99 to just to make your reporting easier then the I consider that data as corrupted. What if there are other consumer apart from reporting which need genuine data?

I would rather write an intelligent query for the report. For example, if you use ISNULL(columnname, 99), it would return 99 whenever the column value is NULL.