Database Reference
In-Depth Information
Another thing we may want to do is select only certain rows, for example, everyone
born after 1 January, 1960:
MariaDB [test]> SELECT * FROM employees
-> WHERE birthday > '1960-01-01';
+----+---------+---------------+-----------+------------+
| id | surname | givenname | pref_name | birthday |
+----+---------+---------------+-----------+------------+
| 3 | Snow | Lorenzo | NULL | 1964-04-03 |
| 4 | Smith | George Albert | George | 1970-04-04 |
+----+---------+---------------+-----------+------------+
2 rows in set (0.00 sec)
The > sign is a comparison operator. Just like in math, it means greater than.
There are many other comparison operators. See https://mariadb.com/kb/en/
comparison-operators/ for a complete list.
The arrow ( -> ) in the previous output example is not something we
typed. The mysql command-line client program inserted it to show
that we pressed the Enter key before ending our command with a
semicolon ( ; ), and so the command we are entering is continuing on a
second line. If we pressed Enter and just forgot to end our command,
we can just type a semicolon and press Enter again. In the previous
example, I did it on purpose to split the command onto two lines to
make it easier to read.
Our output, by default, is sorted based on the order in which it was inserted into the
database. For a list of employees we really should sort on the surname column. To
do this we use an ORDER BY clause as follows:
MariaDB [test]> SELECT * FROM employees ORDER BY surname;
+----+----------+---------------+-----------+------------+
| id | surname | givenname | pref_name | birthday |
+----+----------+---------------+-----------+------------+
| 5 | McKay | NULL | NULL | NULL |
| 4 | Smith | George Albert | George | 1970-04-04 |
| 3 | Snow | Lorenzo | NULL | 1964-04-03 |
| 1 | Taylor | John | John | 1958-11-01 |
| 2 | Woodruff | Wilford | Will | 1957-03-01 |
+----+----------+---------------+-----------+------------+
5 rows in set (0.00 sec)
 
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