SQL in the Wild » Blog Archive » NOT EXISTS vs NOT IN. Continuing with the mini-series on query operators, I want to have a look at NOT EXISTS and NOT IN.
Previous parts of this miniseries are: Just one note before diving into that. The examples I’m using are fairly simplistic and that’s intentional. I’m trying to find what, if any, are the performance differences in a benchmark-style setup. I’ll have some comments on more complex examples in a later post. Introduction to Indexes. Good indexes are the key to good performance in SQL Server and the key to creating good indexes is to understand what indexes are and how SQL Server uses them to evaluate queries.
In this first part of a three part series, I’m going to look at the very basics of what indexes are, what types exist in SQL and how they’re used. What is an index? Myth Directory. SQLAlchemy and You. Written on Tuesday, July 19, 2011 Without doubt are most new Python web programmers these days chosing the Django framework as their gateway drug to Python web development.
As such many people's first experience with a Python ORM (or maybe an ORM altogether) is the Django one. When they are later switching to something else they often find SQLAlchemy unnecessarily complex and hard to use. Why is that the case? I made a quick poll on Twitter about why people prefer the Django ORM over SQLAlchemy and I got back a few interesting results.