You are confusing two concepts.

To concatenate strings is to combine two strings into one. The string concatenation operator is & in VB and . in Perl.

VB:
var1 = "abc" & var2

Perl (Concatenation):
$var1 = 'abc' . $var2

Perl (Interpolation):
$var1 = "abc$var2";

Perl (Concatenation using join):
$var1 = join('', 'abc', $var2);
[download]

In VB, all statements must be on the same line. The _ operator allows you to break a statement into multiple lines. This has nothing to do with string concatenation. Perl doesn't require a continuation operator. Instead, one must tell Perl where the statement ends using ;.

VB:
var = func(var1, var2, var3)

Perl:
$var = func($var1, $var2, $var3);

VB:
var = func( _
   var1, _
   var2, _
   var3 _
)

Perl:
$var = func(
   $var1,
   $var2,
   $var3
);
[download]

Together:

VB:
stmt = "SELECT *" & _
       "  FROM table" & _
       " ORDER BY field"

Perl:
$stmt = "SELECT *"
      . "  FROM table"
      . " ORDER BY field"

Perl (Since SQL servers treats newlines as whitespace):
$stmt = "
   SELECT *
     FROM table
    ORDER BY field
";
[download]