'SELECT name FROM table WHERE 1 = 1'
мы записываем его ввиде DB::table('table')->select('name')->where('1', '=', 1);
if ($request->man && $request->woman) {
$query->where('sex', 'male')->where('sex', 'female');
} elseif ($request->man && !$request->woman) {
$query->where('sex', 'man');
} elseif (!$request->man && $request->woman) {
$query->where('sex', 'female');
} else {
$query->where('sex', null);
}
if ($request->man) {
$query->where('sex', 'man');
}
if ($request->woman) {
$query->where('sex', 'female');
}