Bert Wagner gives us several reasons why VARCHAR(8000) can be a bad fit for data types:
When first learning SQL Server, I had the brilliant idea of defining every column on my table as VARCHAR(8000). After all, the VARCHAR datatype only consumes as much storage space as the string itself (plus two bytes), so even if I defined the max length of a column as 8000, I wouldn’t be wasting storage space if my data was smaller than that.
My development life would be easier too since I wouldn’t have to think about the kind of data I was storing in my columns; I could define everything as VARCHAR(8000) once and never have to go back to make any changes. Brilliant!
While I was correct about not wasting storage space, it turns out the idea of making every column VARCHAR(8000) is a terrible idea.
Click through to learn why.