Previous chapters discussed the important topics of organizing your tables well and getting data in to them. In this chapter, we will cover a key objective that makes the others pay off: retrieving the data stored in a database. This is commonly called a database query.
The simplest way to retrieve data from a MySQL or MariaDB
database—to select data—is to use the SQL statement,
SELECT. We used this SQL statement a few times in previous
chapters. In this chapter, we will cover it in greater detail. It’s not
necessary to know or use all of the may options, but some techniques such as
joining tables together are basic to using relational databases.
We’ll begin this chapter by reviewing the basics of the
SELECT statement, and then progress to more involved variants.
When you finish this chapter, you will hopefully have a good understanding
of how to use
SELECT for most of your needs as you start out as
a database developer, as well as be prepared for the many possibilities and
special situations that may arise over the years of developing databases
with MySQL and MariaDB.
In previous chapters, especially in the exercises, you were asked to enter data into the tables that we created and altered in the chapters of the previous part of this book. Entering data on your own was good for training purposes, but we now need much more data in our database to better appreciate the examples in this chapter. If you haven’t done so already, go to this book’s website and download ...