Database Reference
In-Depth Information
terisk to select all of the columns, but named the specific ones we want. We also chose
columns from two tables.
On the second line, we say to select these columns listed from
books
and from
status_names
. The
JOIN
clause is where we named the second table.
In the
WHERE
clause,on the third line, we tell MySQL to match the values of the
status
column from
books
to the values of the
status_id
column from the
status_names
table. This is the point in which the rows from each will be joined. If
the idea of joining tables seems difficult, don't worry about it at this point. I've included it
just to show you what can be done with MySQL and MariaDB. I'll explain joins more
fully later.
When we created
books
, we could have made
status
a text or character field and
entered the words
Active
or
Inactive
for each row. But if you have a table with thousands
or maybe millions of rows of data, entering
0
or
1
is much easier and you're less likely to
make typos (e.g., you might enter
Actve
sometimes). Databases are tedious, but creating
tables with better structures and using better written SQL statements makes them less tedi-
ous and helps you to leverage your time andresources.
