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I'm getting error when i try to refer index with string

The error:"Notice: Undefined index: subject_id in C:\Program Files\EasyPHP at the line 17"

  $Pages=mysql_query("select * from pages where subject_id ={$Row["subject_id"]}",$Connection);
                    while($PageRow=mysql_fetch_array($Pages))
                    {
                        echo"<li>{$PageRow["menu_name"]}</li>";
                    }

But it works fine if i use the integer index instead,

    echo"<li>{$Row[2]}</li>";

I've seen the same code in an example code and it works, is the problem with the MySQl database setting?

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6 Answers

up vote 1 down vote accepted

You've given the error as

Notice: Undefined index: subject_id in C:\Program Files\EasyPHP at the line 17

, so subject_id should be the problem. In the example code, you have menu_name as the key of the array. So, which one is it? What are the columns of this table? The code that you've given will work if there is a "menu_name" column in the table.

The problem should be the name of the column that you want to access. Check that again.

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thank you very much. – major Oct 7 at 12:01
You're welcome. Remember - var_dump() is your best friend in this kind of situations. – Nikoloff Oct 7 at 12:21
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up vote 1 down vote

You are not fetching the result row as an associative array & although you are using curly braces I would change the quotes to single quotes just for consistency . Change to this:

 $SubjectSet = mysql_query("select * from subjects" , $Connection);
 while($Row = mysql_fetch_assoc($SubjectSet)) // change to mysql_fetch_assoc()
 {
     echo "<li>{$Row['menu_name']}</li>"; // use single quotes
 }

you can check what keys & values are begin returned by using:

$SubjectSet = mysql_query("select * from subjects" , $Connection);
 while($Row = mysql_fetch_assoc($SubjectSet)) // change to mysql_fetch_assoc()
 {
     print_r($Row);
 }
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Technically there's nothing wrong with mysql_fetch_array to fetch associative arrays - by default it should fetch an associative array with both an integer index and the field names as keys (MYSQL_BOTH is the default) - but if it's been set to MYSQL_NUM for some reason, then yes... – CD001 Oct 7 at 11:20
@Cd001 true but the error says that the index is undefined, thus above solution to force the associative array. plus mysql_fetch_assoc looks cleaner – Mark Oct 7 at 11:28
thanx for help i did a mistake, i posted the wrong part of code previously :$ sorry. – major Oct 7 at 12:08
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up vote 0 down vote

:) use MYSQL_ASSOC with mysql_fetch_array() or use mysql_fetch_assoc() instead:

while($Row=mysql_fetch_array($SubjectSet, MYSQL_ASSOC))

or 

while($Row=mysql_fetch_assoc($SubjectSet))

You can read this. I tried to make this as short as possible for you!

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thanx for help i did a mistake, i posted the wrong part of code previously :$ sorry. – major Oct 7 at 12:08
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up vote 0 down vote

Have you tryed?

$SubjectSet=mysql_query("select * from subjects",$Connection);
while($Row=mysql_fetch_array($SubjectSet)) {
    echo"<li>".$Row["menu_name"]."</li>";
}
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thanx but the same happens – major Oct 7 at 11:14
The it has to be another line: "Undefined index: subject_id" There is no subject_id in this line. – MasterCassim Oct 7 at 11:15
echo"<li>".{$Row["menu_name"]}."</li>"; is somewhat superfluous since you've broken the string and concatenated it anyway ... the second example (echo"<li>".$Row["menu_name"]."</li>"; ) is better. – CD001 Oct 7 at 11:22
thanx for help i did a mistake, i posted the wrong part of code previously :$ sorry. – major Oct 7 at 12:08
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up vote 1 down vote

You could try using single quotes instead:

 $SubjectSet=mysql_query("select * from subjects",$Connection);
  while($Row=mysql_fetch_assoc($SubjectSet))
  {
    echo"<li>{$Row['menu_name']}</li>";// line 17
  }

CORRECTION:

Just noticed you didn't use assoc fetching. Use the mysql_fetch_assoc() method instead if you wish to access columns using their name.

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up vote 0 down vote

It's the quote marks in the echo... you're using double quotes in both instances which will break the string (it shouldn't since you've wrapped it in curly braces, but still...).

Try:

echo"<li>{$Row['menu_name']}</li>";

If that doesn't work - ensure you're fetching an associative array from the database; you may need to pass either the the constant MYSQL_ASSOC or MYSQL_BOTH to the query (though, by default, it should use MYSQL_BOTH).

$Row=mysql_fetch_array($SubjectSet, MYSQL_ASSOC)

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thanx for help i did a mistake, i posted the wrong part of code previously :$ sorry. – major Oct 7 at 12:08
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