my website is always attacked

i have website configured to send me emails when it generates and error

i get tons of error messages

<div class="iw ajw">to me</div> <div class="ajy"></div> <div id=":59y">Error in:http://lovenmarry.com/News/viewnews.aspx?id=8 AND 2501=(SELECT UPPER(XMLType(CHR(60)||CHR(58)||CHR(118)||CHR(97)||CHR(122)||CHR(58)||(SELECT (CASE WHEN (2501=2501) THEN 1 ELSE 0 END) FROM DUAL)||CHR(58)||CHR(108)||CHR(118)||CHR(112)||CHR(58)||CHR(62))) FROM DUAL). Error Message:Incorrect syntax near the keyword 'AND'. 'CHR' is not a recognized built-in function name. Incorrect syntax near '|'. 117.198.221.215 </div><div></div> <div>my idea is to set cookie and block that user from surfing my website</div> <div>any ideas?</div>