MYSQL--獲取數(shù)字串中的最大值

909413335

1. mysql> use test;
   
2. Database changed
   
3. mysql> drop procedure if exists sp1;
   
4. Query OK, 0 rows affected (0.00 sec)
   
5. 
   
6. #create procedure using prepare
   
7. mysql> delimiter //
   
8. mysql> create procedure sp1(str varchar(1000))
   
9.     -> begin
   
10.     -> set @p=concat('select greatest(',str,')');
    
11.     -> PREPARE stmt1 FROM @p;
    
12.     -> EXECUTE stmt1 ;
    
13.     -> DEALLOCATE PREPARE stmt1;
    
14.     -> end;
    
15.     -> //
    
16. Query OK, 0 rows affected (0.00 sec)
    
17. 
    
18. mysql> delimiter ;
    
19. 
    
20. #testing procedure,parameter count is arbitrary
    
21. mysql> call sp1('1,2,3,40,5,4000');
    
22. +---------------------------+
    
23. | greatest(1,2,3,40,5,4000) |
    
24. +---------------------------+
    
25. | 4000 |
    
26. +---------------------------+
    
27. 1 row in set (0.00 sec)
    
28. 
    
29. Query OK, 0 rows affected (0.01 sec)
    
30. 
    
31. mysql> call sp1('1,2,3,40,5');
    
32. +----------------------+
    
33. | greatest(1,2,3,40,5) |
    
34. +----------------------+
    
35. | 40 |
    
36. +----------------------+
    
37. 1 row in set (0.00 sec)
    
38. 
    
39. Query OK, 0 rows affected (0.01 sec)