Drawing Graphs with MySQL

Drawing what with what???!?

Yes you read correctly. Let's suppose we got the following table layout in MySql:

+-------------+--------------+------+-----+---------+----------------+
| Fiel        | Type         | Null | Key | Default | Extra          |
+-------------+--------------+------+-----+---------+----------------+
| id          | int(11)      | NO   | PRI | NULL    | auto_increment |
| createTime  | DateTime     | YES  |     | NULL    |                |
| dur         | integer      | YES  |     | NULL    |                |
+-------------+--------------+------+-----+---------+----------------+

It's a very basic logging table that simply stores generic events, its creation time and the time this event took to run in milliseconds. Lets query that table:

SELECT creationTime, executionTime FROM myLogTable

+---------------------+---------------+
| creationTime        | dur           |
+---------------------+---------------+
| 2013-11-23 13:27:00 |            10 |
| 2013-11-23 13:27:08 |            11 |
| 2013-11-23 13:27:11 |             9 |
| 2013-11-23 13:27:18 |            13 |
| 2013-11-23 13:27:20 |            13 |
| 2013-11-23 13:27:21 |            25 |
| 2013-11-23 13:27:30 |             9 |
| 2013-11-23 13:27:35 |            30 |
| 2013-11-23 13:27:37 |            15 |
| 2013-11-23 13:27:45 |             8 |
+---------------------+---------------+

Obviously this data is a little hard to read, wouldn't it by nice to have some kind of a visualisation?
Let's try this query:

SELECT id, creationTime, executionTime, repeat('|', executionTime) as graph FROM myLogTable

+---------------------+-----+--------------------------------+
| creationTime        | dur | graph                          |
+---------------------+-----+--------------------------------+
| 2013-11-23 13:27:00 |  10 | ||||||||||                     |
| 2013-11-23 13:27:08 |  11 | |||||||||||                    |
| 2013-11-23 13:27:11 |   9 | |||||||||                      |
| 2013-11-23 13:27:18 |  13 | |||||||||||||                  |
| 2013-11-23 13:27:20 |  13 | |||||||||||||                  |
| 2013-11-23 13:27:21 |  11 | |||||||||||                    |
| 2013-11-23 13:27:30 |   9 | |||||||||                      |
| 2013-11-23 13:27:35 |  30 | |||||||||||||||||||||||||||||| |
| 2013-11-23 13:27:37 |  15 | |||||||||||||||                |
| 2013-11-23 13:27:45 |   8 | ||||||||                       |
+---------------------+-----+--------------------------------+

Now we got a graphic representation of the value that shows us anomaly on the first glance.

Where true or false is not enough!

At some point we've found the following code candy in our source code:

function str2bool($str) {
    if ($str === false or $str === "0" or $str === 0 or $str === "" or $str === "false" or $str === "FALSE" or $str === "falsch" or $str === "FALSCH") {
        return false;
    }
    return true;
}

This piece of code is unused and someone forgot about to delete it. But it looks like it was used in one of our externally connected subsystems to translate values like FALSCH, falsch, FALSE to a boolean false. ("falsch" is german for "false")

We're not sure if there were ever values like "FALSCH" in our code - but it's a little bit scary for us ;)