PHP Nested ifs and many conditions not working - php

Question

I have many nested ifs and conditions in my code but it is not giving the desired output. What is the best way to write the following code :
$driver_code = $this->input->post('filter_driver_code');
$unit_code = $this->input->post('filter_unit_code');
$fuel_type = $this->input->post('filter_fuel');
$date_to = $this->input->post('date_to');
$date_from = $this->input->post('date_from');
if (isset($date_from) and isset($date_to) and empty($unit_code) and empty($driver_code) and empty($fuel_type)) {
$sql = "SELECT * FROM fuel_usage where (date between '$date_from' and '$date_to') ";
$result = $this->db->query($sql);
} elseif (isset($driver_code) and isset($unit_code) and isset($fuel_type) and isset($date_from) and isset($date_to)) {
$sql = "SELECT * FROM fuel_usage where driver_code='$driver_code' AND unit_code='$unit_code' AND fuel_type='$fuel_type' and (date between '$date_from' and '$date_to')";
$result = $this->db->query($sql);
} elseif (empty ($date_from) and empty ($date_to) and isset ($unit_code) and isset ($driver_code) and isset ($fuel_type)) {
$sql = "SELECT * FROM fuel_usage where driver_code='$driver_code' AND unit_code='$unit_code' AND fuel_type='$fuel_type'";
$result = $this->db->query($sql);
} else {
$sql="SELECT * FROM FUEL_USAGE";
$result = $this->db->query($sql);
}
It does not give the right output.

Answer 1

Try all check with empty() may be isset() gives you problem cause on post isset for all variable will return true even values blank
if (!empty($driver_code) && !empty($unit_code) && !empty($fuel_type) && !empty($date_from) && !empty($date_to)) {
$sql = "SELECT * FROM fuel_usage where driver_code='$driver_code' AND unit_code='$unit_code' AND fuel_type='$fuel_type' and (date between '$date_from' and '$date_to')";
$result = $this->db->query($sql);
}elseif (!empty($date_from) && !empty($date_to) && empty($unit_code) && empty($driver_code) && empty($fuel_type)) {
$sql = "SELECT * FROM fuel_usage where (date between '$date_from' and '$date_to') ";
$result = $this->db->query($sql);
} elseif (empty($date_from) && empty($date_to) && !empty($unit_code) && !empty($driver_code) && !empty($fuel_type)) {
$sql = "SELECT * FROM fuel_usage where driver_code='$driver_code' AND unit_code='$unit_code' AND fuel_type='$fuel_type'";
$result = $this->db->query($sql);
} else {
$sql="SELECT * FROM FUEL_USAGE";
$result = $this->db->query($sql);
}
or try in short way
$sql = "SELECT * FROM fuel_usage where 1 ";
if (!empty($driver_code)) {
$sql .= " AND driver_code='$driver_code' ";
}
if (!empty($unit_code)) {
$sql .= " AND unit_code='$unit_code' ";
}
if (!empty($fuel_type)) {
$sql .= " AND fuel_type='$fuel_type' ";
}
if (!empty($date_from) && !empty($date_to)) {
$sql .= " AND date between '$date_from' and '$date_to' ";
}
$result = $this->db->query($sql);

Answer 2

if (!empty($driver_code) && !empty($unit_code) && !empty($fuel_type) && !empty($date_from) && !empty($date_to)) {
$sql = "SELECT * FROM fuel_usage where driver_code='$driver_code' AND unit_code='$unit_code' AND fuel_type='$fuel_type' and (date between '$date_from' and '$date_to')";
$result = $this->db->query($sql);
}
elseif(!empty ($unit_code) && !empty ($driver_code) && !empty ($fuel_type)) {
$sql = "SELECT * FROM fuel_usage where driver_code='$driver_code' AND unit_code='$unit_code' AND fuel_type='$fuel_type'";
$result = $this->db->query($sql);
}
elseif (!empty($date_from) and !empty($date_to)) {
$sql = "SELECT * FROM fuel_usage where (date between '$date_from' and '$date_to') ";
$result = $this->db->query($sql);
} else {
$sql="SELECT * FROM FUEL_USAGE";
$result = $this->db->query($sql);
}