my $sql = qq{ SELECT a.somedata1,       }
        . qq{        a.somedata2,       }
        . qq{        a.somedata3,       }
        . qq{        [...]              }
        . qq{ FROM table1 a,            }
        . qq{      table2 b,            }
        . qq{      table3 c             }
        . qq{ WHERE a.somedata4 > ?     }
        ;

$sql .=   qq{   AND a.somedata5 <= ?    }
        . qq{   AND [...]               }
        if some_perl_code_condition1;

$sql .=   qq{   AND b.somedata6 >= ?    }
        . qq{   [...]                   }
        if some_perl_code_condition2;

$sql .=   qq{ ORDER BY somedata7        };