my @intervals = (
["{ts'2012-07-01 00:00:00.000'}", "{ts'2012-07-02 00:00:00.000'}","{ts'2012-07-01 00:00:00.000'}", "{ts'2012-07-02 00:00:00.000'}"],
["{ts'2012-07-02 00:00:00.000'}", "{ts'2012-07-03 00:00:00.000'}","{ts'2012-07-02 00:00:00.000'}", "{ts'2012-07-03 00:00:00.000'}"]);


my $dbh = DBI-> connect('dbi:ODBC:DSN=WCPM-DB1;UID=TEST;PWD=pass') or die "CONNECT ERROR! :: $DBI::err $DBI::errstr $DBI::state $!\n";

my $sql2 = <<EOSQL;
SELECT *, DATEDIFF(n,MIN_TIME,MAX_TIME) AS MINS_DIFF 
		FROM
			(SELECT Login_ID, MIN(TimeStamp) AS MIN_TIME,MAX(TimeStamp) AS MAX_TIME
			FROM 
				(SELECT Login_ID,  AuditChrt_TimeStamp AS TimeStamp,
					Patient_ID
				FROM 		
					(SELECT Login_ID, AuditChrt_TimeStamp, Patient_ID
					FROM TopsData.dbo.AUDT_AuditChrt
					WHERE Login_ID IN ('ZZZZZ0004R','ZZZZZ00050','ZZZZZ0006J','ZZZZZ0006P','ZZZZZ0007A')
									AND AuditChrt_TimeStamp > ?	
									AND AuditChrt_TimeStamp < ?) AS A
	UNION ALL
			SELECT Login_ID, AuditMedication_TimeStamp AS TimeStamp, Patient_ID
			FROM 
				(SELECT Login_ID, AuditMedication_TimeStamp, Patient_ID
				FROM TopsData.dbo.AUDT_AuditMedication
	 			WHERE Login_ID IN ('ZZZZZ0004R','ZZZZZ00050','ZZZZZ0006J','ZZZZZ0006P','ZZZZZ0007A')
									AND AuditMedication_TimeStamp > ?		
									AND AuditMedication_TimeStamp < ?) AS B
			) AS A
	GROUP BY Login_ID) AS A;							
EOSQL
my $sth = $dbh->prepare($sql2);

foreach my $interval (@intervals) {
	$sth->execute(@$interval);
	my @row;
	while (@row = $sth->fetchrow_array) {  # retrieve one row at a time
		print  join(", ", @row), "\n";

ERROR: DBD::ODBC::st failed: Conversion failed when converting data and/or time from character string.