Please take a look at the Codex to see how to prepare your statement:

// Example straight copy-paste from Codex
$metakey    = "Harriet's Adages";
$metavalue  = "WordPress' database interface is like Sunday Morning: Easy.";

$wpdb-&gt;query( $wpdb-&gt;prepare( 
    "
        INSERT INTO $wpdb-&gt;postmeta
        ( post_id, meta_key, meta_value )
        VALUES ( %d, %s, %s )
    ", 
    10, 
    $metakey, 
    $metavalue 
) );


Try this with your code too (it's about security).

passing variables as parameters to stored procedures via wpdb from php-script
i can't understand how to solve this issue: using an appropriate substitution, evaluate this integral:
$$
\int \frac{1+x²}{\sqrt{1+x}}\mathrm{d}x
$$
can any one solve this so i can understand how to do this.
