I tried to use the data from this form which is located in my main page - index.php.

    <center> 
<form action="search.php" method="post"> 
<input type="text" name="search" size="30" /> 

<select name='wheretosearch'>
    <option value='Articles'>Articles</option>
    <option value='Users'>Members</option>
    </select>

<input type="submit" value="Search" /> 
</form> 
</center>

This is the main part of search.php code:

    include "all/config.php";

    $search = $_REQUEST['search'];  //Getting the words


    $split = split(" ",$search);  //If there is more than one I spit them.

     foreach ($split as $array => $value) 
{       $NewResult .= $value;
        }

    $wheretosearch = $_POST['wheretosearch'];

        if ($wheretosearch = 'Articles')
        {$Results = mysql_query("SELECT * FROM bgarticles WHERE title LIKE '%$value%' OR description LIKE '%$value%' OR text LIKE '%$value%' OR tags LIKE '%$value%' OR date LIKE '%$value%' OR author LIKE '%$value%' OR ip LIKE '%$value%' "); 

        while($row = mysql_fetch_array($Results))
    { 
        echo "<div class='top'>";
        echo "<span class='title'>";
        echo "<a href=details.php?id=$row[id]>";
        echo $row['title'];
        echo "</a>";
        echo "</span> <br><br>";
        echo "<span class='author'>";
        echo $row['author'];
        echo "</span>";
        echo "<span class='date'> Date: ";
        echo $row['date'];
        echo "</span> <br><br><br>";
        echo "<br><br></div>" ;
        echo "<div class='bottom'><br><br></div>";
    } 
    }


        if ($wheretosearch = 'members') 
        {$Results2 = mysql_query("SELECT * FROM members WHERE username LIKE '%$value%' OR firstname LIKE '%$value%' OR lastname LIKE '%$value%' "); 

            while($row2 = mysql_fetch_array($Results2))
    { 
        echo "<div class='top'>";
        echo "<span class='title'>";
        echo "<a href=details.php?id=$row2[id]>";
        echo $row2['username'];
        echo "</a>";
        echo "</span> <br><br>";
        echo "<span class='author'>";
        echo $row2['firstname'];
        echo "</span>";
        echo "<span class='date'> Date: ";
        echo $row2['date'];
        echo "</span> <br><br><br>";
        echo "<br><br></div>" ;
        echo "<div class='bottom'><br><br></div>";
    } 

        }

No matter I do it always shows data from both mysql tables. Why?