Getting record from database that has empty field

Question

I have the following lines of code to retrieve records from a database:

    $dbh = new PDO("mysql:host=$hostname;dbname=$dbname; charset=utf8;", $username, $password);
        $sql = $dbh->prepare("SELECT * FROM usa WHERE code = :code AND window1 = :oldrepeat AND spare <> :americinn  AND  url IS NOT NULL ORDER BY user ASC");
       $sql->execute(array(':code' => $code, ':oldrepeat' => $oldrepeat, ':americinn' =>$americinn));
        /*** fetch the results ***/
  $result = $sql->fetch();

Amongst other criteria, this query is supposed to return records that only have some content in the field called url, but this is not happening. It is returning records that also have an empty url field.

I assume that I am doing something fundamentally wrong but cannot see what it is.

Can anyone shed some light please?

Best wishes

NULL != empty btw.

Funk Forty Niner
– Funk Forty Niner

2016-04-14 15:19:30 +00:00
Commented Apr 14, 2016 at 15:19 — Funk Forty Niner
– Funk Forty Niner, Commented Apr 14, 2016 at 15:19

A J · Accepted Answer · 2016-04-14 15:26:32Z

1

Well, write your query in following way:

SELECT * FROM usa WHERE code = :code AND window1 = :oldrepeat AND spare <> :americinn  AND  !ISNULL(url) ORDER BY user ASC

ISNULL is an inbuilt MySQL function that checks if value of a column is null. By using ! (negation), you will get only required rows.

In case if a column has blank value, you can try url!=''.

answered Apr 14, 2016 at 15:26

A J

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