PHP / mySQL - for loop doesn't work properly

Question

I have these lines of code:

$user = $_SESSION['name'];
$con = mysqli_connect("localhost","root","","db_shop");
$sql = mysqli_query($con,"SELECT * FROM tbl_cart WHERE `user` = '$user' AND `done` = '0'");

while( $result = mysqli_fetch_assoc( $sql ) ){

    $file = $result['items'];
    $res = explode(",",$file);
    $total = 0;
    $tmp = count( $res );
    for( $i = 0 ; $i <= $tmp; $i++ ){

        $sql = "SELECT * FROM `tbl_details` WHERE `file_name` = '".$res[$i]."'";
        echo $sql;
        $sql = mysqli_query( $con, "SELECT * FROM `tbl_details` WHERE `file_name` = '".$res[$i]."'");
        while( $res = mysqli_fetch_assoc( $sql ) ){
            $total += $res['price'];
        }
        echo "<script>alert('$total');</script>";
    }
}

where $res[1] must contain a value of 1000 from my database, but it just gives me a null value.

As you can see I tried to echo out $sql, $res[0] returned the right one but $res[1] returned:

SELECT * FROM `tbl_details` WHERE `file_name` = ''

Any help would be appreciated thanks.

SELECT * FROM tbl_details WHERE file_name = '1.jpg'SELECT * FROM tbl_details WHERE file_name = ''SELECT * FROM tbl_details WHERE file_name = '' this is the output — Thamus
– Thamus, Commented Oct 20, 2015 at 22:31
i think the looping is right my only problem is why my $res[1] returns nothing — Thamus
– Thamus, Commented Oct 20, 2015 at 22:32
If you were to add print_r($res); immediately after $res = explode(",",$file); what would you get in the array? Does this contain all the values you would expect? — Professor Abronsius
– Professor Abronsius, Commented Oct 20, 2015 at 22:33
yep it returns just what i expect. Array ( [0] => 1.jpg [1] => 10.jpg ) — Thamus
– Thamus, Commented Oct 20, 2015 at 22:35

Professor Abronsius · Accepted Answer · 2015-10-20 22:40:34Z

2

I wonder whether it is because the inner sql statement references the same variable name $sql? Changed the inner variable names ....

$user = $_SESSION['name'];
$con = mysqli_connect("localhost","root","","db_shop");
$sql = mysqli_query($con,"SELECT * FROM tbl_cart WHERE `user` = '$user' AND `done` = '0'");

while( $result = mysqli_fetch_assoc( $sql ) ){

    $file = $result['items'];
    $res = explode(",",$file);
    $total = 0;
    $tmp = count( $res );

    for( $i = 0 ; $i < $tmp; $i++ ){

        $sql_inner = "SELECT * FROM `tbl_details` WHERE `file_name` = '".$res[$i]."'";
        #echo $sql_inner;

        $res_inner = mysqli_query( $con, "SELECT * FROM `tbl_details` WHERE `file_name` = '".$res[$i]."'");
        while( $row = mysqli_fetch_object( $res_inner ) ){
            $total += $row->price;
        }
        echo "<script>alert('$total');</script>";
    }
}

answered Oct 20, 2015 at 22:40

Professor Abronsius

33.9k5 gold badges36 silver badges49 bronze badges

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

2 Comments

Thamus Over a year ago

Dude it worked like a miracle . :D thanks ^-^v i almost died here . xD

Alex Over a year ago

since you commented echo $sql_inner; you can comment echo "<script>alert('$total');</script>"; as well ;-)

Alex · Accepted Answer · 2015-10-20 22:37:14Z

0

You should change $i <= $tmp to $i < $tmp.

Because count $tmp = count( $res ); returns number of elements but not the max index of element.

for( $i = 0 ; $i < $tmp; $i++ ){

and here you should use another variable name not $res:

    while( $row = mysqli_fetch_assoc( $sql ) ){
        $total += $row['price'];
    }

answered Oct 20, 2015 at 22:37

Alex

17.3k1 gold badge31 silver badges52 bronze badges

2 Comments

Thamus Over a year ago

tried it tho, didn't worked for me. $res[1] still returns nothing.

Alex Over a year ago

@YesSir you repeat $res[1] so many time in comments, but I don't see any code line that outputs that $res[1] somewhere in your code provided.

Collectives™ on Stack Overflow

PHP / mySQL - for loop doesn't work properly

2 Answers 2

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related