Learning Mysql

Again, what’s important is getting familiar with the columns in each table, as we’ll make use of these frequently later when we’re learning about querying. Notice also that because all of these three entities are weak, each table contains the primary key columns from the table it’s related to. For example, the track table contains artist_id
,
album_id
, and track_id
, because the combination of all three is required to uniquely identify a track.
In the next section, we show you how to explore the data that’s stored in the music database and its tables.
The SELECT Statement and Basic Querying Techniques
Up to this point, you’ve learned how to install and configure MySQL, and how to use the MySQL monitor. Now that you understand the music database, you’re ready to start exploring its data and to learn the SQL language that’s used by all MySQL clients.
In this section, we introduce the most commonly used SQL keyword, and the only one that reads data from a database the
SELECT
keyword. We also explain some basic elements of style and syntax, and the features of the
WHERE
clause, Boolean operators, and sorting (much of this also applies to our later discussions of INSERT, UPDATE, and
DELETE)
. This isn’t the end of our discussion of SELECT you’ll find more in Chapter where we show you how to use its advanced features.
Single Table SELECTs
The most basic form of
SELECT
reads the data in all rows and columns from a table. Start the monitor and choose the music database:
mysql> use music;
Database changed
Let’s retrieve all of the data in the artist table:
mysql> SELECT * FROM artist;
+-----------+---------------------------+
| artist_id | artist_name |
+-----------+---------------------------+
| 1 | New Order |
| 2 | Nick Cave & The Bad Seeds |
| 3 | Miles Davis |
| 4 | The Rolling Stones |
| 5 | The Stone Roses |
| 6 | Kylie Minogue |
+-----------+---------------------------+
6 rows inset sec)
The output has six rows, and each row contains the values for the artist_id and artist_name columns. We now know that there are six artists in our database and can seethe names and identifiers for these artists.

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