RPAD()

RPAD()

函数说明

函数 RPAD(str,len,padstr) 在字符串 str 右侧使用 padstr 进行填充，直至总长度为 len 的字符串，最后返回填充后的字符串。如果 str 的长度大于 len，那么最后的长度将缩减至 len。若 len 为负数，则返回 NULL。

函数语法

1. > RPAD(str,len,padstr)

参数释义

参数	说明
str	必要参数，被填充的字符串。CHAR 与 VARCHAR 类型均可。
len	必要参数，需要填充到的总长度。
padstr	必要参数，用于填充的字符串。CHAR 与 VARCHAR 类型均可。

示例

1. > drop table if exists t1;
2. > CREATE TABLE t1(Student_id INT,Student_name VARCHAR(100),Student_Class CHAR(20));
3. > INSERT INTO t1
4. VALUES
5. (1,'Ananya Majumdar', 'IX'),
6. (2,'Anushka Samanta', 'X'),
7. (3,'Aniket Sharma', 'XI'),
8. (4,'Anik Das', 'X'),
9. (5,'Riya Jain', 'IX'),
10. (6,'Tapan Samanta', 'X');
11. > SELECT Student_id, Student_name,RPAD(Student_Class, 10, ' _') AS LeftPaddedString FROM t1;
12. +------------+-----------------+------------------+
13. | Student_id | Student_name    | LeftPaddedString |
14. +------------+-----------------+------------------+
15. |          1 | Ananya Majumdar | IX _ _ _ _       |
16. |          2 | Anushka Samanta | X _ _ _ _        |
17. |          3 | Aniket Sharma   | XI _ _ _ _       |
18. |          4 | Anik Das        | X _ _ _ _        |
19. |          5 | Riya Jain       | IX _ _ _ _       |
20. |          6 | Tapan Samanta   | X _ _ _ _        |
21. +------------+-----------------+------------------+
22. > SELECT Student_id, rpad(Student_name,4,'new') AS LeftPaddedString FROM t1;
23. +------------+------------------+
24. | Student_id | LeftPaddedString |
25. +------------+------------------+
26. |          1 | Anan             |
27. |          2 | Anus             |
28. |          3 | Anik             |
29. |          4 | Anik             |
30. |          5 | Riya             |
31. |          6 | Tapa             |
32. +------------+------------------+
33. > SELECT Student_id, rpad(Student_name,-4,'new') AS LeftPaddedString FROM t1;
34. +------------+------------------+
35. | Student_id | LeftPaddedString |
36. +------------+------------------+
37. |          1 | NULL             |
38. |          2 | NULL             |
39. |          3 | NULL             |
40. |          4 | NULL             |
41. |          5 | NULL             |
42. |          6 | NULL             |
43. +------------+------------------+
44. > SELECT Student_id, rpad(Student_name,0,'new') AS LeftPaddedString FROM t1;
45. +------------+------------------+
46. | Student_id | LeftPaddedString |
47. +------------+------------------+
48. |          1 |                  |
49. |          2 |                  |
50. |          3 |                  |
51. |          4 |                  |
52. |          5 |                  |
53. |          6 |                  |
54. +------------+------------------+