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how to check the maximum id in the database. what is the query for that?

Posted on 2009-07-01
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Last Modified: 2012-05-07
how to check the maximum id in the database. what is the query for that?
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Question by:designersx
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7 Comments
 
LVL 7

Expert Comment

by:szewkam
ID: 24752637
The latest id in db? "SELECT id FROM table ORDER BY id DESC LIMIT 1" or "SELECT MAX(id) FROM table"
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Author Comment

by:designersx
ID: 24752812
the output is Resource id #3
<?php
	$db_host="localhost";
	$db_name="modified_cms";
	$username="root";
	$password="";
	$db_con=mysql_connect($db_host,$username,$password) or die("connection not build".mysql_error());
	$db=mysql_select_db($db_name) or die("database not build".mysql_error());
	
	$sql = "select max(id) from products";
	$query = mysql_query($sql);
	echo $query;
?>

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Author Comment

by:designersx
ID: 24752824
i am not able to get the latest id from the database, please look at the code i am using.
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LVL 7

Accepted Solution

by:
szewkam earned 125 total points
ID: 24752871
mysql_query returns type resource not data. If you want to display max use code from snippet:
<?php
        $db_host="localhost";
        $db_name="modified_cms";
        $username="root";
        $password="";
        $db_con=mysql_connect($db_host,$username,$password) or die("connection not build".mysql_error());
        $db=mysql_select_db($db_name) or die("database not build".mysql_error());
        
        $sql = "select max(id) from products";
        $query = mysql_query($sql);
        list($id) = mysql_fetch_row($query);
        echo $id;
?>

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Author Comment

by:designersx
ID: 24752912
it is exactly right , sir can we use mysql_insert_id(). can u please tell the usage of that.
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LVL 7

Expert Comment

by:szewkam
ID: 24752960
well you can use mysql_insert_id if you want to retrieve id right after executing the query. In other cases if you using queries to add some data to other tables you can't be sure that this function gave you the expected value.
Usage is given on: http://pl2.php.net/manual/en/function.mysql-insert-id.php
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Author Comment

by:designersx
ID: 24753023
thanks a lot.
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