This just annoys me so much. The sum of an empty set of integers is zero, not undefined.

However neither Oracle nor MySQL understand this. I can only assume this variation from common sense and mathematics is considered the “best practices” definition of the SQL SUM function.

mysql> desc email_box;
| box_size_bytes | int(10)     |

mysql> select count(*) from email_box;
|        0 |

mysql> select sum(box_size_bytes) from email_box;
| NULL |

This entry was posted on Wednesday, November 29th, 2006 at 3:52 pm and is filed under Broken, Databases. You can subscribe to Adrian's blog. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.