Question

考虑以下查询：

DECLARE @t1 TABLE(
    CompanyId INT, 
    DirectorName VARCHAR(100));

INSERT INTO @t1
   VALUES
      (1,'D11'),
      (1,'D12'),
      (1,'D13'),
      (1,'D14'),
      (1,'D15'),
      (1,'D16'),
      (2,'D21'),
      (2,'D22'),
      (2,'D23'),
      (2,'D24'),
      (2,'D25'),
      (2,'D26'),
      (2,'D27'),
      (2,'D28'),
      (2,'D29'),
      (2,'D210'),
      (3,'D31'),
      (3,'D32'),
      (3,'D33');

SELECT * FROM @t1

它仅返回该ID的companyId和一组董事。如何生成以下输出：

 CompanyId | Director1| Director2| Director3|Director4| Director5| Director6| Director7| Director8| Director9| Director10|
-----------------------------------------------------------------------------------------------------------------------------
       1           D11        D12       D13       D14        D15         D16       NULL        NULL       NULL      NULL
       2           D21        D22       D23       D24        D25         D26       D27         D28        D29       D210 
       3           D31        D32       D33       NULL       NULL        NULL      NULL        NULL       NULL      NULL

上述查询技巧的出处是每个公司的董事人数都不相同。在上面的示例中，第2行具有最高的控制器数目，这意味着最终输出内其他ID的相关列将为空。如何创建以上输出。

为了清楚起见，在此示例中，每个id（companyId）的结果不会超过10列（导演）。

Answer 1

您可以使用PIVOT使用以下解决方案：

Traceback (most recent call last):
  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/django/core/management/__init__.py", line 357, in execute
    django.setup()
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/django/apps/registry.py", line 114, in populate
    app_config.import_models()
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/django/apps/config.py", line 211, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/akshay/django/google_login/login/models.py", line 3, in <module>
    from oauth2client.contrib.django_util.models import CredentialsField
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/oauth2client/contrib/django_util/__init__.py", line 365, in <module>
    oauth2_settings = OAuth2Settings(django.conf.settings)
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/oauth2client/contrib/django_util/__init__.py", line 341, in __init__
    info = _get_oauth2_client_id_and_secret(settings_instance)
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/oauth2client/contrib/django_util/__init__.py", line 277, in _get_oauth2_client_id_and_secret
    return _load_client_secrets(secret_json)
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/oauth2client/contrib/django_util/__init__.py", line 255, in _load_client_secrets
    client_type, client_info = clientsecrets.loadfile(filename)
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/oauth2client/clientsecrets.py", line 165, in loadfile
    return _loadfile(filename)
  File "/home/akshay/django/google_login/myvenv/lib/python3.6/site-packages/oauth2client/clientsecrets.py", line 122, in _loadfile
    obj = json.load(fp)
  File "/usr/lib/python3.6/json/__init__.py", line 299, in load
    parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
  File "/usr/lib/python3.6/json/__init__.py", line 354, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.6/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.6/json/decoder.py", line 355, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Invalid control character at: line 1 column 451 (char 450)

demo on dbfiddle.uk

Answer 2

使用CTE，ROW_NUMBER和条件聚合，您可以做到这一点

每家公司的董事人数不超过10名

;with cteGetDirectorNum
AS(
    select
         T.CompanyId
        ,T.DirectorName
        ,DirectorNum    ='Director'+CONVERT(VARCHAR(10), Row_Number()over( partition by T.CompanyId order by T.CompanyId, T.DirectorName))
    from
        @t1     T
)
SELECT
     N.CompanyId
    ,Director1      = MAX(CASE WHEN N.DirectorNum = 'Director1' THEN n.DirectorName ELSE NULL END)
    ,Director2      = MAX(CASE WHEN N.DirectorNum = 'Director2' THEN n.DirectorName ELSE NULL END)
    ,Director3      = MAX(CASE WHEN N.DirectorNum = 'Director3' THEN n.DirectorName ELSE NULL END)
    ,Director4      = MAX(CASE WHEN N.DirectorNum = 'Director4' THEN n.DirectorName ELSE NULL END)
    ,Director5      = MAX(CASE WHEN N.DirectorNum = 'Director5' THEN n.DirectorName ELSE NULL END)
    ,Director6      = MAX(CASE WHEN N.DirectorNum = 'Director6' THEN n.DirectorName ELSE NULL END)
    ,Director7      = MAX(CASE WHEN N.DirectorNum = 'Director7' THEN n.DirectorName ELSE NULL END)
    ,Director8      = MAX(CASE WHEN N.DirectorNum = 'Director8' THEN n.DirectorName ELSE NULL END)
    ,Director9      = MAX(CASE WHEN N.DirectorNum = 'Director9' THEN n.DirectorName ELSE NULL END)
    ,Director10     = MAX(CASE WHEN N.DirectorNum = 'Director10' THEN n.DirectorName ELSE NULL END)
FROM
    cteGetDirectorNum N
GROUP BY N.CompanyId

将行转换为一组ID的列

2 个答案: