Koha error

The following fatal error has occurred:

Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) at /var/www/perpustakaan/lib/C4/Context.pm line 666.
Compilation failed in require at /var/www/perpustakaan/lib/C4/VirtualShelves/Page.pm line 26.
BEGIN failed--compilation aborted at /var/www/perpustakaan/lib/C4/VirtualShelves/Page.pm line 26.
Compilation failed in require at /var/www/perpustakaan/opac/cgi-bin/opac/opac-shelves.pl line 23.
BEGIN failed--compilation aborted at /var/www/perpustakaan/opac/cgi-bin/opac/opac-shelves.pl line 23.