I have a script that has worked for years, but now it's throwing an error, pointing to the line that attempts to connect to my database.

line 3: use DBI;

...

line 20: my $dbh = DBI->connect('DBI:mysql:database_name1;host=localho
+st;port=3306', 'username', 'password')
    or die "Couldn't open database: $DBI::errstr; stopped";
line 22: my $dbh2 = DBI->connect('DBI:mysql:database_name2;host=localh
+ost;port=3306', 'username', 'password')
    or die "Couldn't open database: $DBI::errstr; stopped";
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the error message is as follows:

install_driver(mysql) failed: Can't locate DBD/mysql.pm in @INC 
(@INC contains: /home/domainname/public_html/cgi-bin/ //perl5/lib/perl
+5 
//perl5/lib/perl5/x86_64-linux-thread-multi //perl/usr/local/lib64/per
+l5 
//perl/usr/local/share/perl5 //perl/usr/lib64/perl5/vendor_perl 
//perl/usr/share/perl5/vendor_perl //perl/usr/lib64/perl5 
//perl/usr/share/perl5 /usr/local/lib64/perl5 /usr/local/share/perl5 
/usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/p
+erl5 /usr/share/perl5 .) at (eval 18) line 3.
Perhaps the DBD::mysql perl module hasn't been fully installed,
or perhaps the capitalisation of 'mysql' isn't right.
Available drivers: DBM, ExampleP, File, Gofer, Mem, Proxy, SQLite, Spo
+nge.
 at /home/domainname/public_html/cgi-bin/events_db_embed.pl line 20.
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should I replace DBI with one of the following? DBM, ExampleP, File, Gofer, Mem, Proxy, SQLite, Sponge.

just as an addendum, I search for DBI as an available module, and it's not listed on my host