How to find out if parent have children in php mysql-CodePudding

It have two table parent table and children table

Parent Table

id   page-title    page-content

Children Table (where parent_id = id) id from parent table

child_id   parent_id   child-title   child-content

Now How to find out if parent have any children

<?php
//parent table
$data = $conn->query("SELECT * FROM parent_page ORDER BY id DESC");
while($rows = $data->fetch(PDO::FETCH_OBJ) ):
    $parent_id = $rows->id;
?>

<?php 
    //chlidren table
    $child_data= $conn->query("SELECT * FROM children_page WHERE parent_id = $parent_id ");
    while($child_rows = $child_data->fetch(PDO::FETCH_OBJ) ):
         $child_rows->parent_id;
 ?>
<?php
//requirement check if parent have children (how to check if parent have children or not)
if('parent have children'){
    then echo children content;
}else{
    echo parent content;
}
?>

<?php endwhile; endwhile;?>

CodePudding user response：

Get the number of rows in the child query. If it's more than zero, the parent has children.

You should also use a prepared query instead of substituting variables directly into the SQL.

<?php
$child_data = $conn->prepare("SELECT * FROM children_page WHERE parent_id = :parent");
$child_data->bindParam(':parent', $parent_id);
//parent table
$data = $conn->query("SELECT * FROM parent_page ORDER BY id DESC");
while($rows = $data->fetch(PDO::FETCH_OBJ) ):
    $parent_id = $rows->id;
?>

<?php 
    //chlidren table
    $child_data->execute();
    if ($child_data->rowCount()) {
        // parent has children
        while($child_rows = $child_data->fetch(PDO::FETCH_OBJ) ): 
            // echo children content
            ?>
<?php endwhile;
}else{
    echo parent content;
}
?>

<?php endwhile;?>

CodePudding user response：

I Have no idea in PHP. But you can do this by changing your query.

Select * 
from Children c
left Join Parent p on p.id = c.parent_id

You can check parent_id value.

If Parent_id value null then no parent avaialble. If it is not null parent is Available.

CodePudding user response：

hp //chlidren table $child_data= $conn->query("SELECT * FROM children_page WHERE parent_id = $parent_id "); while($child_rows = $child_data->fetch(PDO::FETCH_OBJ) ): $child_rows->parent_id; ?>