javascript防止SQL注入

<SCRIPT language="javascript">
function Check(theform)
{?
?if (theform.UserName.value=="")
?{
alert("请输入用户名！")
theform.UserName.focus();
return (false);
?}
?if (theform.Password.value == "")
?{
alert("请输入密码！");
theform.Password.focus();
return (false);
?}
}
function IsValid( oField )
{
?re= /select|update|delete|exec|count|‘|"|=|;|>|<|%/i;
?$sMsg = "请您不要在参数中输入特殊字符和SQL关键字！"
?if ( re.test(oField.value) )
?{
alert( $sMsg );
oField.value = ‘‘;
oField.focus();
return false;
?}
}
</SCRIPT>

<input name="UserName" type="text" maxlength="20" id="UserName" onblur="IsValid(this);" style="width:125px;" />
<input name="Password" type="password" maxlength="20" id="Password" onblur="IsValid(this);" style="width:125px;" />