Highlight table row in different colors based on values from database in php

Question

The code below has dynamic drop down list, that users chooses preferred brand and model, accordingly the table is generated in the webpage which results of brand, model and year . Now the code needs to group all the same year with different models and highlight them with set of different colors for each year accordingly. An expected results is attached as image.

// (___ & !!!) or (ALL & ___) or (ALL & ALL)
if ((!isset($_POST['model']) || ($_POST['brand'] == 'ALL' && empty($_POST['model']))) || ($_POST['brand'] == 'ALL' && $_POST['sip'] == 'ALL')) {
    $query1 = 'SELECT DISTINCT brand,model,year FROM `carlist` ORDER BY brand,model,year';
}
// (... & ...) or (... & ALL)
else if (!empty($_POST['brand']) && (empty($_POST['model']) || ($_POST['model'] == 'ALL'))) {
    $query1 = 'SELECT DISTINCT brand,model,year FROM `carlist` WHERE brand="'.$_POST['brand'].'" ORDER BY brand,model,year';
}
// (ALL & ...) or (ALL & notALL)
else if ($_POST['brand'] == 'ALL' && (!empty($_POST['model']) && $_POST['model'] != 'ALL')) {
    $query1 = 'SELECT DISTINCT brand,model,year FROM `carlist` WHERE model="'.$_POST['model'].'" ORDER BY brand,model,year';
}
else {
    $query1 = 'SELECT DISTINCT brand,model,year FROM `carlist` WHERE brand="'.$_POST['brand'].'" AND model="'.$_POST['model'].'" ORDER BY brand,model,year';
}
//echo $_POST['brand'].'<br />'.$_POST['model'];

echo '<table border=1><tr><th>BRAND</th><th>MODEL</th><th>YEAR</th></tr>';
$result1 = mysqli_query($con, $query1);


    while($row1 = mysqli_fetch_array($result1)){
    //echo'<tr><td>'.$row1['brand'].'</td><td>'.$row1['model'].'</td><td>'.$row1['year'].'</td></tr>';

        $query2= 'SELECT DISTINCT brand,model,year, count(*) `number` FROM `carlist` WHERE brand="'.$_POST['brand'].'" GROUP BY `year` HAVING count(*) > 1';
        $result2= mysqli_query($con, $query2);
        $count=0;


        while($row2 = mysqli_fetch_array($result2)){

            if ( $row2['year'] == $row1['year']) {
            $count=1;
            }

            //$intersect = array_intersect($row1,$row2);
            //echo $intersect[1];


        }

        $bgcolor = "#FF8C00"; 
        if($count==1){
            echo '<tr style="background-color: tomato;" ><td>'.$row1['brand'].'</td><td>'.$row1['model'].'</td><td>'.$row1['year'].'</td></tr>';

        }else {

            echo'<tr><td>'.$row1['brand'].'</td><td>'.$row1['model'].'</td><td>'.$row1['year'].'</td></tr>';
        } 

    }


echo '</table>';

Answer 1

Method 1:

This won't need to do a nested loop. This first method will only work if your row is arranged by year.

/* DEFINE THIS VARIABLE FIRST BEFORE YOUR LOOP */
$yearstorage = ""; /* STORAGE FOR YOUR YEAR AND COMPARISON LATER */
$randomcolor = '#' . strtoupper(dechex(rand(256,16777215))); /* GENERATE RANDOM COLOR */

/* START OF YOUR LOOP */
while($row1 = mysqli_fetch_array($result1)){

  $res = mysqli_query($con,"SELECT * FROM carlist WHERE year=".$row1['year']."");
  if(mysqli_num_rows($res) > 1){ /* IF YEAR HAS ONLY ONE ROW */
    $randomcolor = "#ffffff";
  }

  if(empty($yearstorage)){ /* START OF FIRST ROW */
    ?>
      <tr style="background-color: <?php echo $randomcolor ?>;">
    <?php
    $storecolor = $randomcolor;
  }

  else if($yearstorage == $row1["year"]){ /* IF LAST YEAR ROW IS THE SAME AS THE CURRENT YEAR ROW */
    ?>
      <tr style="background-color: <?php echo $storecolor ?>;">
    <?php
  } 

  else { /* IF THE LAST YEAR ROW IS NOT THE SAME WITH THE CURRENT YEAR ROW */
    $randomcolor = '#' . strtoupper(dechex(rand(256,16777215))); /* GENERATE NEW RANDOM COLOR */
    ?>
      <tr style="background-color: <?php echo $randomcolor ?>;">
    <?php
    $storecolor = $randomcolor;
  }

  $yearstorage = $row1["year"]; /* STORE THE CURRENT YEAR FOR COMPARISON ON THE NEXT LOOP */

    ?>
        <td><?php echo $row1['brand']; ?></td>
        <td><?php echo $row1['model']; ?></td>
        <td><?php echo $row1['year']; ?></td>
      </tr>
    <?php

} /* END OF WHILE LOOP */

Method 2:

This second method will work even if your row is not arrange in year. Even if arranged by different column name which I would refer more to you.

You have to create a loop to get all the year distinctly, and store the color and year in an array, and compare and get them on your main loop.

No need to do a nested loop also. But two separated loop.

As you will notice, this code is also shorter than the first method.

If a year contains one row only, it will have a white background.

$counter = 0; /* DETERMINER OF THE COLOR TO BE USED LATER */
$res = mysqli_query($con,"SELECT DISTINCT year FROM carlist");
while($row = mysqli_fetch_array($res)){
  $randomcolor = '#' . strtoupper(dechex(rand(256,16777215))); /* GENERATE NEW RANDOM COLOR */
  /* STORE THE COLOR AND YEAR IN AN ARRAY */

  $res2 = mysqli_query($con,"SELECT * FROM carlist WHERE year = ".$row['year']."");
  if(mysqli_num_rows($res2) > 1){ /* IF YEAR IS USED MORE THAN ONCE */
    $colorstorage[$counter] = $randomcolor;
  }
  else { /* ELSE, IT WILL HAVE A WHITE BACKGROUND */
    $colorstorage[$counter] = "#ffffff";
  }
  $yearstorage[$counter] = $row['year'];
  $counter = $counter + 1; /* INCREMENT COUNTER */
} /* END OF LOOP THAT STORES THE COLOR AND YEAR IN AN ARRAY */

/* START OF YOUR MAIN LOOP */
while($row1 = mysqli_fetch_array($result1)){

  $key = array_search($row1["year"],$yearstorage);
  ?>
    <tr style="background-color: <?php echo $colorstorage[$key]; ?>;">
      <td><?php echo $row1['brand']; ?></td>
      <td><?php echo $row1['model']; ?></td>
      <td><?php echo $row1['year']; ?></td>
    </tr>
  <?php

} /* END OF YOUR MAIN LOOP */

Answer 2

Create function what generates random color

function getColor($year){
  return '#'.substr(md5($year), 0, 6);
}

In your while loop

// Get color for current year
// Same years will be colored with same color
$bgColor = getColor($row1['year']);

// Print table row
echo '<tr style="background-color: '.$bgColor.';"><td>'.$row1['brand'].'</td><td>'.$row1['model'].'</td><td>'.$row1['year'].'</td></tr>';

So your while loop will be

while($row1 = mysqli_fetch_array($result1)){

    // Delete extra while and if condition

    $bgColor = getColor($row1['year']);
    echo '<tr style="background-color: '.$bgColor.';"><td>'.$row1['brand'].'</td><td>'.$row1['model'].'</td><td>'.$row1['year'].'</td></tr>';
}

NOTE: Your queries are vulnerable to SQL injection. Please see this answer on how to prevent it.

NOTE 2: Since your background colors are generated automatically, it may happen that text is not easily readable.