Hendak buat bandingan jualan antara 2 bulan seperti jan dan feb

bandingan2_tanya.php

<?php
/*
//anggap $bulan adalah array seperti ini

$bulan = array('rangka',
  'jan', 'feb', 'mac', 'apr', 
  'mei', 'jun', 'jul', 'ogo', 
  'sep', 'okt', 'nov', 'dis');
*/
class Bandingan_Tanya extend Tanya
{
  
  public cariBandingan($bulan, $cari, $id)
  {// kalau guna union sql
    foreach ($bulan as $key => $myTable):
      if ( ! in_array($key,array(0,1)))
      {
        $sebelum = $bulan[$key - 1];
        $semasa = $myTable;
        // hasil
        $hasilSebelum = 'format(sebelum.hasil,0)';
        $hasilSemasa = 'format(semasa.hasil,0)';
        $hasil = "concat($hasilSebelum,'<br>',$hasilSemasa) as hasil";
        $peratus = " format(  (($hasilSemasa-$hasilSebelum)/$hasilSebelum)*100  ,2) as `Beza Hasil` ";
        // dptLain
        $dptLainSebelum = 'format(sebelum.dptLain,0)';
        $dptLainSemasa = 'format(semasa.dptLain,0)';
        $dptLain = "concat($dptLainSebelum,'<br>',$dptLainSemasa) as hasil";
        $peratus2 = " format(  (($dptLainSemasa-$dptLainSebelum)/$dptLainSebelum)*100  ,2) as `Beza dptLain` ";
        // gaji
        $gajiSebelum = 'format(sebelum.gaji,0)';
        $gajiSemasa = 'format(semasa.gaji,0)';
        $gaji = "concat($gajiSebelum,'<br>',$gajiSemasa) as hasil";
        $peratus3 = " format(  (($gajiSemasa-$gajiSebelum)/$gajiSebelum)*100 ,2) as `Beza Gaji` ";
        // staf
        $stafSebelum = 'format(sebelum.staf,0)';
        $stafSemasa = 'format(semasa.staf,0)';
        $staf = "concat($stafSebelum,'<br>',$stafSemasa) as hasil";
        $peratus4 = " format(  (($stafSemasa-$stafSebelum)/$stafSebelum)*100 ,2) as `Beza Staf` ";
        // sql        
        $sql[] = "SELECT "
             . "$hasil, $peratus, "
             . "$dptLain, $peratus2, "
             . 'semasa.web,'
             . "$gaji, $peratus3, "
             . "$staf, $peratus4, "
             . 'semasa.outlet,semasa.sebab, substring($semasa,5,5) as bulan '
             . "FROM $sebelum as sebelum, $semasa as semasa "
             . "WHERE sebelum.id = semasa.id "
             . "AND semasa.id = '$id' ";
      }
      elseif ( in_array($key,array(0)))
      {
        //
      }
    endforeach;

        // masuk dalam $data
        $senaraiSql = implode("UNION",$sql);
        $data['Kawal'][] = $this->db->select($senaraiSql);
    
    return $data;
    
  }
}

bandingan_tanya.php

<?php
/*
//anggap $bulan adalah array seperti ini

$bulan = array('rangka',
  'jan', 'feb', 'mac', 'apr', 
  'mei', 'jun', 'jul', 'ogo', 
  'sep', 'okt', 'nov', 'dis');
*/
class Bandingan_Tanya extend Tanya
{
  
  public cariBandingan($bulan, $cari, $id)
  {// kalau guna foreach
    foreach ($bulan as $key => $myTable):
      if ( ! in_array($key,array(0,1)))
      {
        $sebelum = $bulan[$key - 1];
        $semasa = $myTable;
        // hasil
        $hasilSebelum = 'format(sebelum.hasil,0)';
        $hasilSemasa = 'format(semasa.hasil,0)';
        $hasil = "concat($hasilSebelum,'<br>',$hasilSemasa) as hasil";
        $peratus = " format(  (($hasilSemasa-$hasilSebelum)/$hasilSebelum)*100  ,2) as `Beza Hasil` ";
        // dptLain
        $dptLainSebelum = 'format(sebelum.dptLain,0)';
        $dptLainSemasa = 'format(semasa.dptLain,0)';
        $dptLain = "concat($dptLainSebelum,'<br>',$dptLainSemasa) as hasil";
        $peratus2 = " format(  (($dptLainSemasa-$dptLainSebelum)/$dptLainSebelum)*100  ,2) as `Beza dptLain` ";
        // gaji
        $gajiSebelum = 'format(sebelum.gaji,0)';
        $gajiSemasa = 'format(semasa.gaji,0)';
        $gaji = "concat($gajiSebelum,'<br>',$gajiSemasa) as hasil";
        $peratus3 = " format(  (($gajiSemasa-$gajiSebelum)/$gajiSebelum)*100 ,2) as `Beza Gaji` ";
        // staf
        $stafSebelum = 'format(sebelum.staf,0)';
        $stafSemasa = 'format(semasa.staf,0)';
        $staf = "concat($stafSebelum,'<br>',$stafSemasa) as hasil";
        $peratus4 = " format(  (($stafSemasa-$stafSebelum)/$stafSebelum)*100 ,2) as `Beza Staf` ";
        // sql        
        $sql = "SELECT "
             . "$hasil, $peratus, "
             . "$dptLain, $peratus2, "
             . 'semasa.web,'
             . "$gaji, $peratus3, "
             . "$staf, $peratus4, "
             . 'semasa.outlet,semasa.sebab, substring($semasa,5,5) as bulan '
             . "FROM $sebelum as sebelum, $semasa as semasa "
             . "WHERE sebelum.id = semasa.id "
             . "AND semasa.id = '$id' ";
        // masuk dalam $data
        $data['Kawal'][] = $this->db->select($sql);
      }
      elseif ( in_array($key,array(0)))
      {
        //
      }
    endforeach;
    
    return $data;
    
  }
}