Retrieve integer value from Database using PHP

Question

I'm increment an ID from my code. When I retrieve the maximum value from database it does't assign to the variable.

I test my query from database SQL then it shows the maximum value. but when I echo it doesn't show.

Here is my code,

<html>
    <body>
        <form enctype="multipart/form-data" method="post" action="test_issue.php">
           <input name="submit" type="submit" id="submit" value="submit"  /> 
        </form>
    </body>
</html>

<?php
    include ("connection.php");
            if(isset($_POST['submit']))
            {               
                    // $queryselect =  "SELECT issued_id FROM pass WHERE pass_id=8";
                    $queryselect= "SELECT MAX(issued_id) FROM pass WHERE status='Issued'";
                    $last_sec_result = mysqli_query($connection,$queryselect );

                    if($last_sec_result!=0)
                    {
                        $last_sec_value = mysqli_fetch_array($last_sec_result);
                        $sec_id_no = $last_sec_value['issued_id'];
                        echo $sec_id_no;   
                    }
                    else
                    {
                        echo $last_sec_result ;
                        echo "database query failed please check data you enter.";
                    }
                    // echo $sec_id_no;
            }
?>

When I retrieve value with a simple select query (SELECT issued_id FROM pass WHERE pass_id=8) it shows the value. I'm stuck with this. Can anyone help me Please.

its on the page. I just echo to check whether value was passed or not. — Hansini Lakshani
– Hansini Lakshani, Commented Jun 22, 2019 at 8:51
@M.Hemant it shows value when use var_dump but when I echo it doesn't show the value. — Hansini Lakshani
– Hansini Lakshani, Commented Jun 22, 2019 at 9:06

alx · Accepted Answer · 2019-06-22 10:44:42Z

1

Your query defines column MAX(issued_id) without alias, so, in fetched record it has some fancy name like... well, MAX(issued_id).

Try to change your query like this (note AS issued_id part):

SELECT MAX(issued_id) AS issued_id FROM pass WHERE status='Issued'

This will make sure fetched record hasissued_id field, and your following code will be able to extract it.

answered Jun 22, 2019 at 10:44

alx

2,3872 gold badges18 silver badges22 bronze badges

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

Comments

JessGabriel · Accepted Answer · 2019-06-22 09:24:20Z

0

1- mysql_query() doesn't return an integer as your condition is waiting for 2- use alias to be sure about the index in the returned result set

include ("connection.php");
        if(isset($_POST['submit']))
        {               
                // $queryselect =  "SELECT issued_id as issued_id FROM pass WHERE pass_id=8";
                $queryselect= "SELECT MAX(issued_id) as issued_id FROM pass WHERE status='Issued'";
                $last_sec_result = mysqli_query($connection,$queryselect );

                if($last_sec_result !== null)
                {
                    $last_sec_value = mysqli_fetch_array($last_sec_result);
                    $sec_id_no = $last_sec_value['issued_id'];
                    echo $sec_id_no;   
                }

                else
                {
                    echo $last_sec_result ;
                    echo "database query failed please check data you enter.";
                }
                // echo $sec_id_no;
        }

answered Jun 22, 2019 at 9:24

JessGabriel

1,0929 silver badges19 bronze badges

2 Comments

Hansini Lakshani Over a year ago

I converted by using (int)$variable then it shows 0 but the value is not zero.

JessGabriel Over a year ago

SELECT MAX(issued_id) as issued_id FROM pass WHERE status='Issued', run this query directly in phpmyadmin or whatever.

Vladimir Vukanac · Accepted Answer · 2019-06-22 11:04:23Z

0

So if previous answers do not give you an expected solution then there are no rows with status set to exact same content 'Issued', that is why query return empty result array.

SELECT issued_id, status FROM pass;
# must return some rows

SELECT MAX(issued_id) AS issued_id FROM pass;
# must return some numbers

SELECT MAX(issued_id) AS issued_id FROM pass WHERE status='Issued';
# should return expected value

answered Jun 22, 2019 at 11:04

Vladimir Vukanac

99418 silver badges32 bronze badges

Collectives™ on Stack Overflow

Retrieve integer value from Database using PHP

3 Answers 3

Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related