如何以降序显示多个表的数据库结果

I have a keyword search on my site that allows visitors to search for specific things. My msysql db has 15 tables and for the search feature I use a UNION ALL to join them all so visitor can search all the tables simultaneously. The problem is all the results are in ascending order. How do I get the results in descending order.

SELECT *  
FROM table1  
WHERE keyword LIKE %s OR id  LIKE %s  

UNION ALL 

SELECT *  
FROM table2  
WHERE keyword LIKE %s OR id  LIKE %s  

UNION ALL 

SELECT *  
FROM table3   
WHERE keyword LIKE %s OR id  LIKE %s 

SELECT * 
FROM 
  ( SELECT * 
    FROM table1
    WHERE keyword LIKE '%s' OR id  LIKE '%s'    ---notice the quotes
  UNION ALL SELECT .......
  ) AS tmp 
ORDER BY keyword DESC

In such case I'd suggest you to normalize the database and put all the keywords in the same table. If you separate the keywords according to its type use a column type to indicate it.

The following query will do what you are requiring.

SELECT * 
FROM   ((SELECT * 
         FROM   table1 
         WHERE  keyword LIKE '%s' 
                 OR id LIKE '%s') 
        UNION ALL 
        (SELECT * 
         FROM   table2 
         WHERE  keyword LIKE '%s' 
                 OR id LIKE '%s') 
        UNION ALL 
        (SELECT * 
         FROM   table3 
         WHERE  keyword LIKE '%s' 
                 OR id LIKE '%s')) AS bigtable 
ORDER  BY `id`;