Mastering SQL: Queries - Take It Easy

You don’t have to be an SQL guru to realize that adding another condition to the WHERE clause will not pick up your query to a higher level of complexity, since this task can be normally accomplished by a beginner. That’s not a surprise though, taking into account that filtering is perhaps the most common operation when it comes to SQL queries. So it is natural to assume that SQL was designed with filtering in mind.Some other SQL coding tasks however may not seem so easy to accomplish, including: aggregating data at different levels, using non-equi joins, fabricating data sets, and handling nulls. As you will learn in this text though, the queries for such tasks do not look frightening once you have them implemented.To run the queries provided in this text, you will need access either to MySQL or to Oracle Database (both have versions that you can download and use for free). To be used in other database systems, some adjustments may be necessary.