【问题标题】：Converting ANSI operators in SQL在 SQL 中转换 ANSI 运算符
【发布时间】：2016-11-25 22:53:54
【问题描述】：

在将以下 2 个查询转换为 ANSI 兼容代码时需要帮助。我的代码使用 =* 运算符，我需要将它们转换为右外连接。我已经给了它一个很好的尝试，但是，无法获得预期的结果。

查询 1

SELECT m.MatterID, m.MatterType,
    m.HasSuppressionOrder, m.Complexity, 
    m.DateReceived, m.DateCompleted,
    ph.OfficerID, pe.Surname + ', ' + pe.GivenNames, h1.Result
FROM   CMS.MATTER m,
    CMS.PHASE ph,
    CMS.PERSON pe,
    CMS.HEARING h1
WHERE             
    (m.DateCompleted BETWEEN '2015-10-29 00:00:00' and '2015-10-30 00:00:00') 
    AND (ph.MatterID = m.MatterID 
    and ph.PhaseSeq = (SELECT MAX(ph2.PhaseSeq) FROM CMS.PHASE ph2 where ph2.MatterID = m.MatterID)) 
    AND (pe.PersonNo = (SELECT mp.PersonNo FROM CMS.MATTER_PERSON mp
            WHERE mp.MatterID = m.MatterID and mp.MatterPersonType = 'DEF')) 
    AND (h1.MatterID =* m.MatterID and --NON ANSI JOIN OPERATORS THAT NEED CONVERSION
    h1.PhaseSeq =* ph.PhaseSeq and --NON ANSI JOIN OPERATORS THAT NEED CONVERSION
    h1.HearingDateTime =* (SELECT MAX(h2.HearingDateTime)FROM CMS.HEARING h2 WHERE h2.MatterID = m.MatterID))
ORDER BY m.MatterID

查询 2

SELECT  m.MatterID,
    m.MatterType,
    m.HasSuppressionOrder,
    m.DateReceived,
    ISNULL (ph.OfficerID, 'No Phase'),
    ISNULL (pe.Surname, 'No Accused Registered') + ', ' + pe.GivenNames,
    m.Complexity,
    m.ProgramCode,
    m.Comments,
    m.StaffGroup,
    m.StaffSubGroup
FROM   CMS.MATTER m,
    CMS.PHASE ph, 
    CMS.PERSON pe
WHERE m.DateReceived BETWEEN '2015-09-30 00:00:00' AND '2015-10-30 00:00:00'
    AND       ph.MatterID =* m.MatterID -- Taken care
    AND       ph.PhaseSeq =* (
        SELECT  MAX( PhaseSeq )
        FROM   CMS.PHASE
        WHERE MatterID = m.MatterID -- Taken care
    )
    AND pe.PersonNo =* (
        SELECT  PersonNo
        FROM   CMS.MATTER_PERSON
        WHERE MatterID = m.MatterID
           AND       MatterPersonType = 'DEF'
    )

我尝试转换查询 2 并编写以下内容：

SELECT  m.MatterID,
    m.MatterType,
    m.HasSuppressionOrder,
    m.DateReceived,
    ISNULL (ph.OfficerID, 'No Phase'),
    ISNULL (pe.Surname, 'No Accused Registered') + ', ' + pe.GivenNames,
    m.Complexity,
    m.ProgramCode,
    m.Comments,
    m.StaffGroup,
    m.StaffSubGroup
FROM   CMS.PHASE ph
right join CMS.MATTER m ON ph.MatterID = m.MatterID
RIGHT JOIN CMS.PERSON pe ON ((SELECT  PersonNo FROM   CMS.MATTER_PERSON WHERE MatterID = m.MatterID AND MatterPersonType = 'DEF')= pe.PersonNo)
RIGHT JOIN CMS.PHASE ph2 ON ((SELECT  MAX(PhaseSeq) FROM CMS.PHASE ph WHERE ph.MatterID = m.MatterID)=ph2.PhaseSeq)
WHERE (m.DateReceived BETWEEN '2015-09-30 00:00:00' AND '2015-10-30 00:00:00')

=============================================

但是，有些不对劲。

【问题讨论】：

您期待什么？什么不正确 - “语法不正确”或“数据不符合预期”？
重写的 ON 条件下的那些子选择是......可疑的。我不确定我什至了解这些条件应该做什么。通常，连接条件识别一个表中的一列和另一个表中的一列，并以某种方式测试它们的关系。

标签： sql tsql outer-join

【解决方案1】：

请记住，通常可以通过交换表将右连接重写为左连接。在我看来，把它变成左连接，即使是旧式的语法，也更容易理解。

SELECT ...
FROM   CMS.MATTER m,
    CMS.PHASE ph, 
    CMS.PERSON pe
WHERE ...
AND m.MatterID *= ph.MatterID
AND (SELECT ...) *= ph.PhaseSeq
AND (SELECT ...) *= pe.PersonNo

这使得您可以将其转换为从CMS.MATTER 中选择，并左连接CMS.PHASE 和CMS.PERSON：

SELECT ...
FROM CMS.MATTER m
LEFT JOIN CMS.PHASE ph
ON ph.MatterID = m.MatterID
AND ph.PhaseSeq = (SELECT ...)
LEFT JOIN CMS.PERSON pe
ON pe.PersonNo = (SELECT ...)

【讨论】：

【解决方案2】：

我认为是这个（QUERY2）：

SELECT
    m.MatterID,
    m.MatterType,
    m.HasSuppressionOrder,
    m.DateReceived,
    ISNULL (ph.OfficerID, 'No Phase'),
    ISNULL (pe.Surname, 'No Accused Registered') + ', ' + pe.GivenNames,
    m.Complexity,
    m.ProgramCode,
    m.Comments,
    m.StaffGroup,
    m.StaffSubGroup
FROM CMS.MATTER m
INNER JOIN CMS.MATTER_PERSON mp
  ON mp.MatterID = m.MatterID AND mp.MatterPersonType = 'DEF'
LEFT JOIN CMS.PERSON pe ON pe.PersonNo = mp.PersonNo
OUTER APPLY
(
  SELECT TOP 1 ph.OfficerID
  FROM CMS.PHASE ph
  WHERE ph.MatterID = m.MatterID
  ORDER BY ph.PhaseSeq DESC
) ph
WHERE m.DateReceived BETWEEN '2015-09-30 00:00:00' AND '2015-10-30 00:00:00'

CMS.MATTER 肯定是必须的部分，最好从它开始并让outer 加入其余表，而不是构建大量令人困惑的right 加入。

不需要到 ph 的双重链接，但我不确定它应该是什么 - outer apply 或 cross apply。 MAX( PhaseSeq ) 是强制部分，所以使用cross apply 可能更正确。但是原始代码中有ISNULL(OfficerID, '')，它告诉我们可能没有相应的值......因为我们得到TOP 1 DESC，所以不需要MAX。

pe.PersonNo =* (SELECT PersonNo 应该总是返回一行 - 否则它会失败 - 所以，我想，我们可以在没有任何 TOP 或 MAX 的情况下加入它。

【讨论】：