可以使用整数索引访问SQL行数组字段，但不能使用字符串索引访问

Question

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

The code:

$Pages = mysql_query("select * from pages where subject_id ={$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?

Answer 1

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);
 }

Answer 2

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.

Answer 3

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.

Answer 4

Have you tryed?

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

Answer 5

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)

Answer 6

:) 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!