Check column is NULL from PHP SQL

Question

How script php can check If there is an empty column in my database in Table the_ad Where column image_link For now my script can not check if there is an empty column What did I do wrong Here is my full code

<?php
$username = "root";
$password = "";
$hostname = "localhost"; 
$dbhandle = mysql_connect($hostname, $username, $password) 
or die("Unable to connect to MySQL");

$selected = mysql_select_db("test",$dbhandle) 
or die("Could not select test");

//fetch tha data from the database
$result_image_link = mysql_query("SELECT image_link FROM test. the_ad");
while ($row_image = mysql_fetch_array($result_image_link)) {
if (empty($result_image_link)) {
    echo "no image_link";
}
else
if (isset($result_image_link)) {
echo "PIC=".$row_image{'image_link'}."<br>";
}
}
mysql_close($dbhandle);
?>

I see the list of column likethis

1. PIC=
2. PIC=
3. PIC=pic3.jpg
4. PIC=pic4.jpg
5. PIC=pic5.jpg
6. PIC=pic6.jpg
7. PIC=pic7.jpg

Why column one and two Not show the message

Thanks to anyone who can help

SELECT image_link FROM test.the_ad WHERE image_link<>'' AND image_link IS NOT NULL — Kristian
– Kristian, Commented Mar 11, 2020 at 8:05

Pieter · Accepted Answer · 2013-07-18 22:23:11Z

2

Use this query: SELECT image_link FROM test WHERE image_link != NULL

Your check is concerning the whole amount of results. Only if there are no results returned from your query, the empty function will return false. You can use the query above or change your if statement to this !empty($row_image['image_link']).

answered Jul 18, 2013 at 22:23

Pieter

1,8431 gold badge12 silver badges16 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Maximus2012 Over a year ago

+1. I think its better to change the query itself rather than getting the values not needed (and then checking for them) even if they are NULL values. This approach may be faster too.

Pieter Over a year ago

If course changing the query will be better, but when you want to show a page with (for example) a list of users with their profile image (if existing), the other approach will be more useful.

Maximus2012 Over a year ago

I see what you are saying. This approach could be combined with the updated query when say you want to display a default image if no image exists. So in OP's case, you need a php check in addition to filtering at MySQL level.

score 2 · Accepted Answer · 2013-07-19 15:38:37Z

2

You can add SQL statement WHERE `image` != ''

$result_image_link = mysql_query("
     SELECT `image` 
     FROM `table` 
     WHERE `image` != ''
");

while($row_image = mysql_fetch_array($result_image_link))
{
    echo "PIC=" . $row_image['image'] . "<br/>";
}

OR

while ($row_image = mysql_fetch_array($result_image_link)) 
{
    echo (isset($row_image['image']) AND $row_image['image'] != '')
        ? "PIC=" . $row_image['image'] . "<br/>" 
        : 'no picture <br/>';
}

edited Jul 19, 2013 at 15:38

answered Jul 18, 2013 at 22:25

user576126

Comments

Ana DEV · Accepted Answer · 2020-03-11 07:37:03Z

0

You can simply use SQL operators IS NULL if you set your DB columns default value as NULL.

Hope this helps.

answered Mar 11, 2020 at 7:37

Ana DEV

1,0202 gold badges18 silver badges41 bronze badges

Collectives™ on Stack Overflow

Check column is NULL from PHP SQL

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related