Good points shammat. Still, if you aren't using PostgreSQL or Oracle and you're not developing for something that might change environments (which has always been the case with me), quotes are still a viable option.

However, I can see two reasons still to follow your advice - first, I think it's good to develop good programming habits, and an individual might have to use Oracle and Postgre or a different environment in the future even if they aren't now. It would be hard to switch if you're used to putting quotes on numeric values. It could cause some bugs or performance issues when you're not paying attention or aren't knowledgeable about your environment.

Second, I particularly like your last point. I didn't quite understand what you were referring to with readability of the code in your first post, but now I do. It's nice to be able to look at a value and know if it is a string or a number in the database. Again, it could avoid bugs.

So, I agree with you and have learned something new. The only situation I might personally still use the single quotes is when I'm using MySQL and I'm dynamically creating a query with variable values that I'm unsure whether they're numeric or string based. Just placing the variable in quotes is a much quicker solution than checking the type and creating two different cases for numeric and string. Anyway, thanks for the explanation shammat.