How to determine if while loop returns nothing from db in php?

Question

I would like to know how can I determine that the while loop that retrieves data from MySQL returns nothing. Here's my code, please take a look at it:

    <?php 
function getAdmins(){
    global $con;
    global $id;
    $get_admin = "select * from admins where id != $id";
    $run_admin = mysqli_query($con,$get_admin);
    while($row_admin = mysqli_fetch_array($run_admin)){
        $id_admin = $row_admin['id'];
        $username_admin = $row_admin['username'];
        $fname_admin = $row_admin['fname'];
        $lname_admin = $row_admin['lname'];
        $email_admin = $row_admin['email'];
        echo '....';
            }
}

Do you mean if mysqli_fetch_array($run_admin) does not return? Returns an array of strings that corresponds to the fetched row or NULL if there are no more rows in resultset. — KiwiJuicer
– KiwiJuicer, Commented Dec 11, 2015 at 15:22
I mean it gets nothing from db .. for example lets say my table is empty at all. How can I show that? — Hello World
– Hello World, Commented Dec 11, 2015 at 15:24
Man , you misunderstood ... I meaned no result found my query because my table is empty — Hello World
– Hello World, Commented Dec 11, 2015 at 15:26
You just check that there is at least one row with results before you fetch them: if (mysqli_num_rows($run_admin)) { /* do while-loop with fetch here */ } — Qirel
– Qirel, Commented Dec 11, 2015 at 15:30

Keilo · Accepted Answer · 2015-12-11 15:25:09Z

3

Before entering the while loop set $loopExecuted = false; Then inside the loop set $loopExecuted = true; After the loop you can check the variable to see if there was at least one iteration of the while loop.

answered Dec 11, 2015 at 15:25

Keilo

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2 Comments

Keilo Over a year ago

Alternatively do your database call before entering the loop. And check the data to see if the loop will execute.

Jon Story Over a year ago

Although this does work, why would you not use mysqli_num_rows - there's no need to manually set a flag when the number of results is known

Dray · Accepted Answer · 2015-12-11 15:44:33Z

2

Count rows using mysqli_num_rows($run_admin);

<?php 

function getAdmins(){
    global $con;
    global $id;
    $get_admin = "select * from admins where id != $id";
    $run_admin = mysqli_query($con,$get_admin);

    if (mysqli_num_rows($run_admin) > 0) {

      while($row_admin = mysqli_fetch_array($run_admin)){
          $id_admin = $row_admin['id'];
          $username_admin = $row_admin['username'];
          $fname_admin = $row_admin['fname'];
          $lname_admin = $row_admin['lname'];
          $email_admin = $row_admin['email'];
          echo '....';
              }

         }
    } else {
       echo 'empty data';
     }

}

edited Dec 11, 2015 at 15:44

Dray

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answered Dec 11, 2015 at 15:25

Aniruddha Chakraborty

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Comments

KiwiJuicer · Accepted Answer · 2015-12-11 15:26:26Z

0

$results = array();

while($row_admin = mysqli_fetch_array($run_admin)){
    results[] = $row_admin;
}

if (empty($results)) {
    echo 'Empty, no results';
}

answered Dec 11, 2015 at 15:26

KiwiJuicer

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3 Comments

KiwiJuicer Over a year ago

Well, usually you need an array anyway, so why using mysqli_num_rows

Qirel Over a year ago

It makes for easier and cleaner code to use mysqli_num_rows(). There's no need to complicate things when there are tools available for that exact need.

Jon Story Over a year ago

@KiwiJuicer - because mysqli_result already contains an array, you're just copying an array (which is slow) for no reason! mysqli_result already has a property $num_rows, which we can use for this. mysqli_num_rows just retrieves that number (which has already been calculated) for virtually no performance cost.

Rene Korss · Accepted Answer · 2015-12-11 15:31:45Z

0

Detect how many rows you found.

$get_admin = "select * from admins where id != $id";
$run_admin = mysqli_query($con, $get_admin);

// Count of rows found
$num_rows = mysqli_num_rows($run_admin);

if($num_rows > 0){
    while($row_admin = mysqli_fetch_array($run_admin)){
        $id_admin = $row_admin['id'];
        $username_admin = $row_admin['username'];
        $fname_admin = $row_admin['fname'];
        $lname_admin = $row_admin['lname'];
        $email_admin = $row_admin['email'];
        echo '....';
    }
}
else{
    // Nothing returned
}

answered Dec 11, 2015 at 15:31

Rene Korss

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Comments

Jon Story · Accepted Answer · 2015-12-11 15:36:26Z

0

$run_admin is just a mysqli_result object, and will be empty if there is nothing returned...

So we can use the following

if(empty($run_admin))
{
    //Nothing returned
}

Or alternately, mysqli_num_rows() does basically the same thing, but explicitly looks at the $num_rows property of the mysqli_result object

if(mysqli_num_rows($run_admin) == 0)
{
    //Nothing returned
}

The latter is probably clearer as it is very obvious that we're saying "if nothing has been returned" rather than "if there is no result" - although the outcome of both is the same, mysqli_num_rows is more descriptive if someone reads the code later.

edited Dec 11, 2015 at 15:36

answered Dec 11, 2015 at 15:34

Jon Story

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2 Comments

Qirel Over a year ago

if(mysqli_num_rows($run_admin) = 0) missing an extra = ;-)

Jon Story Over a year ago

Whoops, I've been working in VB all morning, thanks :p

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