How can i use "mysqli_num_rows" in php?

Question

I am new at Php and i got this code and if there is no post about selected category i want show warning message. I ve tried "mysqli_num_row" but i did not work. Thank you from now : )

 <?php
                        if(isset($_GET['category'])){
                            $post_category_id = $_GET['category'];
                        }

                        $query = "SELECT * FROM posts WHERE post_category_id = $post_category_id ";
                        $select_all_posts_query = mysqli_query($connection, $query);
                        $num_rows = mysqli_num_rows($select_all_posts_query);

                        if($num_rows.count() < 0){
                                echo "<h1 class='text-center'>THERE IS NO POST ABOUT THIS CATEGORY!</h1>";
                                echo "<img style='margin-left:225px;' width='300' class='img-responsive' src='images/sorry.png'/>";
                        }else{
                        while($row = mysqli_fetch_assoc($select_all_posts_query)){
                            $post_id = $row['post_id'];
                            $post_title = $row['post_title'];
                            $post_author = $row['post_author'];
                            $post_date = $row['post_date'];
                            $post_image = $row['post_image'];
                            $post_content = substr($row['post_content'], 0, 50);           
                            ?>
                        <h1 class="page-header">
                Page Heading
                <small>Secondary Text</small>
            </h1>
                        <!-- First Blog Post -->
                        <h2>
                <a href="post.php?p_id=<?php echo $post_id; ?> "><?php echo $post_title ?></a>
            </h2>
                        <p class="lead">
                            by
                            <a href="index.php">
                                <?php echo $post_author ?>
                            </a>
                        </p>
                        <p><span class="glyphicon glyphicon-time"></span>
                            <?php echo $post_date ?>
                        </p>
                        <hr>
                        <a href="post.php?p_id=<?php echo $post_id; ?>"><img width="600" class="img-responsive" src="images/<?php echo $post_image;?>" alt=""></a>
                        <hr>
                        <p>
                            <?php echo $post_content ?>
                        </p>
                        <a class="btn btn-primary" href="#">Read More <span class="glyphicon glyphicon-chevron-right"></span></a>
                        <hr>
                        <?php } }?>

These are all my codes.

It is use as `$num_rows =mysqli_num_rows($select_all_posts_query); if($num_rows >0){---}` — Saty, Mar 17 '16 at 12:36
Simply `if(mysqli_num_rows($select_all_posts_query) > 0)` would work — Sougata Bose, Mar 17 '16 at 12:37
[Your script is at risk for SQL Injection Attacks.](http://stackoverflow.com/questions/60174/how-can-i-prevent-sql-injection-in-php) Learn about [prepared](http://en.wikipedia.org/wiki/Prepared_statement) statements for [MySQLi](http://php.net/manual/en/mysqli.quickstart.prepared-statements.php). — Jay Blanchard, Mar 17 '16 at 12:51

Shraddha Vadnere · Answer 1 · 2016-03-21T11:40:41.993

3

mysqli_num_rows - Returns the number of rows in the result set.

No need to use $num_rows.count()

Use:

if($num_rows <= 0){

    echo "<h1 class='text-center'>THERE IS NO POST ABOUT THIS CATEGORY!</h1>";
    echo "<img style='margin-left:225px;' width='300' class='img-responsive' src='images/sorry.png'/>";

edited Mar 21 '16 at 11:40

answered Mar 17 '16 at 12:43

Shraddha Vadnere

161
1
4

Thank you, it works : ) Have a nice day! – Erdem Nayir Mar 17 '16 at 12:45
2

it has to be: `if($num_rows <= 0)` - otherwise your condition will never be `true`. because you will either have 0 rows or more than 0 rows, but never less than 0. – low_rents Mar 17 '16 at 12:50
Shall I edit your error out, or will you? As this has been accepted it would be usful if it did not contain an error. – RiggsFolly Mar 17 '16 at 12:59

devpro · Answer 2 · 2016-03-17T12:51:18.477

2

Don't know what is it

if($num_rows.count() < 0){

But you are already using mysqli_num_rows() so just replace above mentioned line with:

if($num_rows <= 0){

edited Mar 17 '16 at 12:51

answered Mar 17 '16 at 12:43

devpro

16,184
3
27
38

Oh I didnt see you had edited your answer, I do beg your pardon for duplicating you. – RiggsFolly Mar 17 '16 at 12:56
1

*"Don't know what is it"* - They probably had something going on in their mind where they thought they could use num_rows() and count at the same time. *Who knows* what goes on through people's minds at times ;) – Funk Forty Niner Mar 17 '16 at 13:03
@Fred-ii-: yes u r right, :) – devpro Mar 17 '16 at 13:04

RiggsFolly · Accepted Answer · 2016-03-17T12:55:33.737

1

Or to save an unnecessary variable assignment you could do this

Note I used <= less than or equal and not just < If the query returns no results it will be zero, not something less than zero.

if(mysqli_num_rows($select_all_posts_query) <= 0){
   echo "<h1 class='text-center'>THERE IS NO POST ABOUT THIS CATEGORY!</h1>";
   echo "<img style='margin-left:225px;' width='300' class='img-responsive' src='images/sorry.png'/>";
}else{

edited Mar 17 '16 at 12:55

answered Mar 17 '16 at 12:47

RiggsFolly

93,638
21
103
149

vote for <= suggestion, good work friend.. – devpro Mar 17 '16 at 12:52
@devpro Why thank you sir – RiggsFolly Mar 17 '16 at 12:52
1

@devpro But still the answer with `<` gets accepted. Sometimes I wonder why we bother. – RiggsFolly Mar 17 '16 at 12:54
2

...because, just because Smokey – Funk Forty Niner Mar 17 '16 at 13:01

How can i use "mysqli_num_rows" in php?

3 Answers3