use strict;
sub make_query {
  my @clauses = @_;
  my $count   = 0;
  my $sql     = "select * from employees \n";
  foreach (@clauses) {
    if ($count > 0) { $sql .= ' AND ' }
    else { $sql .= ' WHERE ' }
    foreach ($_) {
      my @criteria = @{$_};
      if ($criteria[2] !~ /^\d+$/) {
        $criteria[2] = "'$criteria[2]'";
      }
      $sql .= " @criteria \n";
    }
    $count++;
  }
  return $sql;
}

my @array = (
  [ 'name',       '=',        'smith' ],
  [ 'salary',     '>',        '50000' ],
  [ 'department', 'NOT LIKE', 'eng%' ]
);

print make_query(@array);


###   select * from employees 
###    WHERE  name = 'smith' 
###    AND  salary > 50000 
###    AND  department NOT LIKE 'eng%'