Essential SQL

Summary

We’ve certainly covered a lot of ground in this chapter, with plenty of code examples to demonstrate the techniques. After discussing some SQL code style issues, we presented a review of join types, highlighting some important areas, such as using outer joins effectively.

Next, you learned how to read the in-depth information provided by EXPLAIN about your SELECT statements. We went over how to interpret the EXPLAIN results and determine if MySQL is constructing a properly efficient query execution plan. We stressed that most of the time, it does. In case MySQL didn’t pick the plan you prefer to use, we showed you some techniques using hints, which you can use to suggest that MySQL find a more effective join order or index access strategy.

Finally, we worked through the advanced subquery and derived table offerings available in MySQL 4.1.

In the next chapter, we build on this base knowledge, turning our attention to two more SQL topics. First, we’ll look at how MySQL optimizes query execution and how you can increase query speed. Then we’ll look at scenarios often encountered in application development and administration, and some advanced query techniques you can use to solve these common, but often complex, problems.