What is the Big-O for SQL select?

Question

What is the Big-O for SQL select, for a table with n rows and for which I want to return m result?

And What is the Big-O for an Updat

Answer 1

I think the real answer can only be determined on a case by case basis (database engine, table design, indices, etc.).

However, if you are a MS SQL Server user, you can familiarize yourself with the Estimated Execution Plan in Query Analyzer (2000) or Management Studio (2005+). That gives you a lot of information you can use for analysis.