Call to undefined function mysql_connect()

При попытке запуска сайта на пхп выдается вот такая строчка
Call to undefined function mysql_connect() ..... bla-bla-bla

Ларчик открывался просто.
После апгрейда системы по какойто причине слетел пакет php5-mysql.
Как только я его поставил командой

apt-get -y install php5-mysql

всё заработало как надо.

Reading package lists...
Building dependency tree...
Reading state information...
The following NEW packages will be installed:
  php5-mysql
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 73.3kB of archives.
After this operation, 283kB of additional disk space will be used.
Get:1 http://ftp.de.debian.org unstable/main php5-mysql 5.3.2-2 [73.3kB]
Fetched 73.3kB in 0s (343kB/s)
Selecting previously deselected package php5-mysql.
(Reading database ... 59519 files and directories currently installed.)
Unpacking php5-mysql (from .../php5-mysql_5.3.2-2_amd64.deb) ...
Processing triggers for libapache2-mod-php5 ...
Reloading web server config: apache2.
Setting up php5-mysql (5.3.2-2) ...
Installing new version of config file /etc/php5/conf.d/mysql.ini ...
Installing new version of config file /etc/php5/conf.d/pdo_mysql.ini ...
Installing new version of config file /etc/php5/conf.d/mysqli.ini ...