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Re: Problem With PDO? or While?

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Call Me Tom <noemail@noemail.com> writes:

> On Thu, 01 Feb 2018 11:11:18 +0000, Ben Bacarisse
> <ben.usenet@bsb.me.uk> wrote:
>
>>Call Me Tom <noemail@noemail.com> writes:
>>
>>> I chose this forum because my sql statements appear to be working.
>>
>>But I don't think you have a PHP problem.
>>
>>> The logged user has all privileges on the database.
>>> The $numin echo prints 2555 which is the number of rows in the table.
>>> The table test is unchanged after running the file.
>>> Here's the code.
>>>
>>> <?php
>>>
>>> require_once('./includes/mysql_connect.php');
>>>
>>> $query = "SELECT report_id,fsacars_rep_url
>>>            FROM test";
>>>
>>> $result=$dbh->query($query);
>>> $numin=$result->rowCount();
>>
>>rowCount is only guaranteed to tell you the number of rows affected by
>>queries that modify a table.  It will work like this for some databases
>>but it's not guaranteed.
>>
>>> echo "$numin";
>>> while($url_orig=$result->FETCH(PDO::FETCH_NUM)) {
>>>         $report_id = $url_orig[0];
>>>         $url_trim = substr($url_orig[1],34);
>>>         $url_new = 'http://localhost/CAA' . $url_trim;
>>>         
>>>         $sql="UPDATE test
>>>                 SET fsacars_rep_url = $url_new
>>>                 WHERE report_id = $report_id";        
>>>         $dbh->exec($sql);
>>
>>You are updating the table before recovering all the rows from a row
>>set.  The exec will invalidate the internal "cursor" that is used to
>>fetch the rows one by one.
>>
>>> } 
>>>
>>> What am I missing?
>
> Do you have a suggestion as to how I can accomplish my goal of
> changing the first 34 characters of the field for every row on the
> table?

This is not a PHP question but an SQL one.  You could do part of the
work in PHP but you could also do all of it in SQL.  I don't have a
simple way to test any examples, so use this with care, but you want
something like:

 update test
   set fsacars_rep_url =
       concat('http://localhost/CAA/', substring(fsacars_rep_url, 35));

(you need to adjust for the different notions of character counting used
by PHP and SQL).

-- 
Ben.

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Thread

Problem With PDO? or While? Call Me Tom <noemail@noemail.com> - 2018-01-31 23:20 -0500
  Re: Problem With PDO? or While? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-01 11:11 +0000
    Re: Problem With PDO? or While? Call Me Tom <noemail@noemail.com> - 2018-02-01 15:54 -0500
      Re: Problem With PDO? or While? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-01 23:27 +0000
        Re: Problem With PDO? or While? Call Me Tom <noemail@noemail.com> - 2018-02-01 23:57 -0500
  Re: Problem With PDO? or While? Jerry Stuckle <jstucklex@attglobal.net> - 2018-02-01 08:19 -0500

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