What is the correct validation to check a input is exists or not in database

Example my MySQL table

content_id  content_u开发者_高级运维ser  content_title        content_slug
---------------------------------------------------------------------
1           1             Hello World          hello-world
2           1             Hello Stackoverflow  hello-stackoverflow
3           2             Fix me               fix-me
4           3             Testing              testing

Update

content_slug is a unique key.

$input = 'Hello World';
$slug  = function_slug($input); // this will be hello-world

/* begin the validation */
$query = $db->query("SELECT * 
                    FROM tbl_content 
                    WHERE content_slug='{$slug}'
                    ");
$data  = $db->fetch($query);
$check = $db->num_rows($query);

if($check == 1) {
$seo = $slug;
 } else {
$seo  = $slug.'-'.time();
}
/* end the validation */

$db->query("UPDATE tbl_content 
            SET content_slug= '{$db->escape($seo)}'
            WHERE content_id ='{$db->escape($id)}'
            AND content_user ='{$db->escape($_SESSION['user_id'])}'
           ");

A bit long :) Here I want to know, what is the correct validation should I use if I want

• If hello-world = current content_user use the first if
• If hello-world <> current content_user and hello-world already exists in database use the } else {

Let me know..

I really don't think you want what you're asking for, but this does what you are asking for in one update query.

UPDATE tbl_content 
            SET content_slug= IF(content_user = '{$db->escape($_SESSION['user_id'])}',
                                 content_slug,
                                 CONCAT(content_slug, '-',  DATE_FORMAT(now(), '%Y%m%d%H%i%s%f')))
            WHERE content_id ='{$db->escape($id)}'

ADDITION

I imagine you want to insert a new row in your table for the different user, in which case, you would need an insert statement. If you want to insert a new row no matter what, then this should work for you:

$slug = "'$db->escape($slug)'";
$db->query("INSERT INTO tbl_content (content_user, content_title, content_slug)
            SELECT '{$db->escape($_SESSION['user_id'])}', '{$db->escape($title)}',
                   IF(EXISTS(SELECT content_id FROM tbl_content WHERE content_slug = $slug),
                      CONCAT($slug, DATE_FORMAT(now(), '-%Y%m%d%H%i%s%f')), $slug)");

If, however, for whatever reason you only want to insert a new row if you don't have the same content_user as before, then you can go with the ugliness here:

$slug = "'{$db->escape($slug)}'";
$user = "'{$db->escape($_SESSION['user_id'])}'";
$db->query("INSERT INTO tbl_content (content_user, content_title, content_slug)
            SELECT $user, '{$db->escape($title)}',
                   IF(EXISTS(SELECT content_id FROM tbl_content WHERE content_slug = $slug),
                      CONCAT($slug, DATE_FORMAT(now(), '-%Y%m%d%H%i%s%f')), $slug)
            FROM tbl_content
            WHERE NOT EXISTS(SELECT content_id FROM tbl_content
                             WHERE content_slug = $slug AND content_user = $user)
            LIMIT 1"));

I think it would be something like this:

$input = 'Hello World';
$slug1  = function_slug($input); // this will be hello-world

$query = $db->query("SELECT * 
                    FROM tbl_content 
                    WHERE content_slug='{$slug1}'
                    ");
$data  = $db->fetch($query);
$check = $db->num_rows($query);

if($check == 1)
$slug2  = $slug1.'-'.time();
$db->query("UPDATE tbl_content 
            SET content_slug= '{$db->escape($slug2)}'
            WHERE content_id ='{$db->escape($id)}'
            AND content_user ='{$db->escape($_SESSION['user_id'])}'
            AND content_slug <> '{$db->escape($slug1)}'
           ");

<> means not equal, != should do as well The extra where will only update if content_slug is not equal to hello-world

 UPDATE <table> SET <field> = <new value> **WHERE** <current User> != <hello world>

I think your db-logic is flawed. but to answer your precise question: just append a UUID and it, whatever it is, will be unique. but what is content_slug and why should it be unique? that is your question for yourself.