1

我需要帮助将两行与以下要求结合起来（使用表格更容易演示..）：

我的架构如下所示：

项目表：

project_id  |   name
--------------------------------
1               Project1
2               Project2
3               Project3

project_program 表

id  |   project_id  |   program_id
-----------------------------------
1       1               1       
2       1               2   
2       3               2

节目表：

program_id  |   type    |   name
---------------------------------------
1               A           test    
2               B           production

选择语句所需的输出：

project_id  |   name     |  A      |    B
-------------------------------------------------------------------
1               Project1    test        production
2               Project2    (null)      (null)
2               Project3    (null)      production

这是我迄今为止设法实现的目标：

SELECT 
  project.*,
  CASE WHEN program.type LIKE 'A' THEN program.name ELSE NULL END AS A,
  CASE WHEN program.type LIKE 'B' THEN program.name ELSE NULL END AS B
FROM 
  project
  LEFT JOIN project_program ON project.project_id = project_program.project_id  
  LEFT JOIN program ON project_program.program_id = program.program_id

它很接近但不完全。现在我的结果如下所示：

project_id  |   name     |  A       |   B
-------------------------------------------------------------------
1               Project1    test        (null)
1               Project1    (null)      production
2               Project2    (null)      (null)
3               Project3    (null)      production

我正在使用 Oracle 11g。

4

1 回答 1

2

您可能可以汇总您拥有的东西 - 例如：

SELECT   id, name, max(A) A, max(b) B
FROM  (
  SELECT 
    project.id, Project.name,
    CASE WHEN program.type LIKE 'A' THEN program.name ELSE NULL END AS A,
    CASE WHEN program.type LIKE 'B' THEN program.name ELSE NULL END AS B
  FROM 
    project
    LEFT JOIN project_program ON project.project_id = project_program.project_id  
    LEFT JOIN program ON project_program.program_id = program.program_id 
  ) X 
GROUP BY  id, name
于 2013-07-02T09:37:23.470 回答