Database Reference
In-Depth Information
We can set the order of any column the way we wish using ORDER BY , and even
specify multiple columns, separating each column with a comma just as we do in the
<what> section.
We can also use pattern matching to select rows when we only know some of the
information. For example, suppose we want to look up an employee whose name
begins with the letters McK but we don't remember the rest. We can look up this
employee using a WHERE clause as follows:
MariaDB [test]> SELECT * FROM employees
-> WHERE surname LIKE "McK%";
+----+---------+-----------+-----------+----------+
| id | surname | givenname | pref_name | birthday |
+----+---------+-----------+-----------+----------+
| 5 | McKay | NULL | NULL | NULL |
+----+---------+-----------+-----------+----------+
1 row in set (0.00 sec)
The percent sign ( % ) is what is known as a wildcard character . It matches zero or
more instances of any character or group of characters. So by specifying the surname
pattern McK% , we are saying that we want any surnames that begin with those letters
and are followed by zero or more other characters. This pattern would match items
such as McKay , McKinsey , McKool , and even McK .
Full documentation of the SELECT command is found at https://mariadb.com/kb/
en/select/ .
The SELECT commands are even more powerful when we start using JOINS to gather
data from multiple tables. For example, if we had an address table along with our
employee table, we could SELECT the names and addresses of all employees who live
in a certain city and whose birthdays are less than a month away so that we can send
them a gift certificate to a restaurant in that city. Full documentation of JOIN syntax
is found at https://mariadb.com/kb/en/join/
 
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