使用mysql的子行的数据表

In MySQL Database, I have two tables Abc and Pqr. In Abc table there's a unique ID, that ID is used in Pqr table as foreign key.

I want to show the parent element as Abc table data and child rows as Pqr table data with respect to Abc unique ID.

Here is my code:

$sqlGetParents="SELECT * from projectrera order by project_id";
$resultGetParents = $conn->query($sqlGetParents);   
?>
<table id="example" class="display" cellspacing="0" width="100%">
    <thead>
        <tr>
            <th></th>
            <th>Project Name</th>
            <th>Builder Id</th>
            <th>Location Id</th>
            <th>Phase</th>
            <th>Status</th>
        </tr>
    </thead>   
      <?php
      while ($row = mysqli_fetch_array($resultGetParents))  { 
       echo " <tr>
            <td class='details-control'></td>
            <td>".$row[1]."</td>
            <td>".$row[2]."</td>
            <td>".$row[3]."</td>
            <td>".$row[8]."</td>
            <td>".$row[15]."</td>
        </tr>";
     }   ?>   
</table>  
<div id="test">
    <table id='example1'>
<?php 
$sqlGetCatWithParent1="SELECT * from info";
 $resultGetCatWithParent1 = $conn->query($sqlGetCatWithParent1);
while ($row3 = mysqli_fetch_array($resultGetCatWithParent1)) {
 echo " <tr>
            <td></td>
            <td>".$row3[1]."</td>
            <td>".$row3[2]."</td>
            <td>".$row3[3]."</td>
        </tr>";
}
?>

Why don't you use the JOIN or Subquery on your select statement? I think that would help you since you're using a relational schema on your tables. Example:

$sqlGetParents =

SELECT abc.*, pqr.* from projectrera abc
  LEFT JOIN info pqr on pqr.project_id = abc.project_id
order by project_id

In your HTML table, I suggest to use FOREACH instead of WHILE.

<?php foreach ($row->result() in $resultGetParents)  { 
  echo "<tr>
        <td class='details-control'></td>
        <td>".<?php echo $row[1]."</td>
        <td>".$row[1]."</td>
        <td>".$row[3]."</td>
        <td>".$row[8]."</td>
        <td>".$row[15]."</td>
    </tr>";
  echo "<tr>
        <td></td>
        <td>".$row[1]."</td>
        <td>".$row[2]."</td>
        <td>".$row[3]."</td>
    </tr>";

} ?>

You can change the $row number based on the results or use text to easily know which columns should be displayed on your table. (i.e $row['project_id'])