If you want to install DBI on OSR 5.0.5 and you built perl with cc
you need to edit the Makefile in DBI-xxx and each subdirectory.
OLD gcc or SCO cc                    New
CC = cc -belf (gcc -belf -fpic)      gcc
CCCDLFLAGS = -KPIC -W1,-Bexport      CCCDLFLAGS = -fpic
CCDLFAGS = -wl,-Bexport              CCDLFLAG =
LD = ld (gcc -belf -G -fpic)         LD = gcc -G -fpic
LDFLAGS = -L/usr/local/lib           LDFLAGS = -L/usr/local/lib
LD = ld (gcc -belf -G -fpic)         LD = gcc -G -fpic
OPTIMISE = Od                        OTIMISE = O1

OLD
CCCFLAGS = -belf -dy -w0 -U M_XENIX -DPERL_SCO5 -I/usr/local/include

NEW
CCCFLAGS = -U M_XENIX -DPERL_SCO5 -I/usr/local/include

This is because the Perl dynaloader will not load the `DBI' modules
if they were compiled with `icc' or `cc'.

You can find a patch for DBI-1.06 at
http://www.zenez.com/zenez/perl5/DBI.patch or
ftp://ftp.zenez.com/pub/zenez/perl5/DBI.patch

$ gunzip DBI-1.06.tar.gz
$ tar xvf DBI-1.06.tar
$ cd DBI-1.06
$ cp /from/download/location/DBI.patch .
$ perl Makefile.PL
$ patch < DBI.patch
$ make
$ make test
$ make install