Question

我的日期有以下表格：

tbl_client
    No  Client Name
    1   John Saw
    2   Michael Ken
    3   Sam Meyer
    4   Eaves Power

AND

tbl_appointment
    No  Name          Date    Type
   1    1           8/4/2017    A
   2    2           5/5/2017    B
   3    3           9/6/2017    C
   4    4           10/6/2017   C
   5    1           12/6/2017   A
   6    2           15/7/2017   B
   7    1           11/10/2017  B
   8    2           21/10/2017  A
   9    3           5/11/2017   B
   10   1           6/11/2017   C
   11   2           5/11/2017   C
  12    4          15/11/2017   A

第一个表包含客户列表，第二个表列出预约日期。我想使用My-SQL生成一个看起来像这样的表：

No  Name          Date         A           B         C
1   John Saw    6/11/2017   12/6/2017   11/10/2017    -
2   Michael Ken 5/11/2017   1/11/2017   15/7/2017     -
3   Sam Meyer   5/11/2017      -           -          -
4   Eaves Power 15/11/2017     -           -      10/6/2017

我尝试了以下查询，但无效：

SELECT 
  a.no,
  a.name,
  b.date,
  d.date AS A 
FROM
  `tbl_client` `a` 
  INNER JOIN `tbl_appointment` `b` 
    ON `a`.`client_id` = `b`.`client_id` 
  LEFT JOIN `tbl_appointment` `d` 
    ON `d`.`client_id` = `a`.`id` 
WHERE `d`.`client_id` = `a`.`id` ;

如何优化查询以向我提供上述报告？

Answer 1

阅读，标记，学习并向内消化以下内容。问题的其余部分是显示问题，最好在应用程序代码中解决：

DROP TABLE IF EXISTS client;

CREATE TABLE client
(client_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,client_name VARCHAR(30) NOT NULL
);

INSERT INTO client VALUES
(1,'John Saw'),
(2,'Michael Ken'),
(3,'Sam Meyer'),
(4,'Eaves Power');

DROP TABLE IF EXISTS appointment;

CREATE TABLE appointment
(appointment_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,client_id INT NOT NULL
,date DATE NOT NULL
,type CHAR(1) NOT NULL
);

INSERT INTO appointment VALUES
( 1,    1 ,          '2017/04/08',   'A'),
( 2,    2 ,          '2017/05/05',   'B'),
( 3,    3 ,          '2017/06/09',   'C'),
( 4,    4 ,          '2017/06/10',   'C'),
( 5,    1 ,          '2017/06/12',   'A'),
( 6,    2 ,          '2017/07/15',   'B'),
( 7,    1 ,          '2017/10/11',   'B'),
( 8,    2 ,          '2017/10/21',   'A'),
( 9,    3 ,          '2017/11/05',   'B'),
(10,    1 ,          '2017/11/06',   'C'),
(11,    2 ,          '2017/11/05',   'C'),
(12,    4 ,          '2017/11/15',   'A');

SELECT c.*
     , a.appointment_id
     , date
     , type 
  FROM client c 
  LEFT 
  JOIN appointment a 
    ON a.client_id = c.client_id
 ORDER 
    BY client_id
     , type;
+-----------+-------------+----------------+------------+------+
| client_id | client_name | appointment_id | date       | type |
+-----------+-------------+----------------+------------+------+
|         1 | John Saw    |              1 | 2017-04-08 | A    |
|         1 | John Saw    |              5 | 2017-06-12 | A    |
|         1 | John Saw    |              7 | 2017-10-11 | B    |
|         1 | John Saw    |             10 | 2017-11-06 | C    |
|         2 | Michael Ken |              8 | 2017-10-21 | A    |
|         2 | Michael Ken |              2 | 2017-05-05 | B    |
|         2 | Michael Ken |              6 | 2017-07-15 | B    |
|         2 | Michael Ken |             11 | 2017-11-05 | C    |
|         3 | Sam Meyer   |              9 | 2017-11-05 | B    |
|         3 | Sam Meyer   |              3 | 2017-06-09 | C    |
|         4 | Eaves Power |             12 | 2017-11-15 | A    |
|         4 | Eaves Power |              4 | 2017-06-10 | C    |
+-----------+-------------+----------------+------------+------+

MySQL生成数据透视表

1 个答案: