如何在View Query中找到表别名？

Question

我现在用C＃为MS-SQL View Query实现View生成器。

如果FROM子句中已有表，我必须将它与现有的表别名一起重用到SELECT子句中

例如，如果我输入“PackOrderPouch”，结果将为“A”，或者如果我输入“Client”，结果将为“R”。

MS-SQL可以通过简单的方式提供表别名，还是可以使用C＃轻松实现？

ALTER VIEW [dbo].[PackOrderRefV]
AS


SELECT 
    A.PackOrderItemOrientedID
,    A.PackOrderItemID
,    A.PouchNo
,    C.PatientNo
,    C.PatientName
,    D.FacilityNo AS LocationNo
,    IIF(D.FacilityName = N'WALK-IN', N'', D.FacilityName) AS LocationName
,    E.FacilityNo AS HospitalNo
,    E.FacilityName AS HospitalName
,    ISNULL(E.FacilityDescription, E.FacilityName) AS HospitalDescription
,    A.AdminDay
,    GETDATE() AS PackedDate
,    ISNULL(H.PrescriptionValue, '') AS BirthDay  --BirthDay (1/2)
,    R.MachineNo  --MachineNo (1/3)
,    Patient_ETC01.PrescriptionItemValue AS Patient_ETC01  --Patient_ETC01 (1/2)

FROM
    PackOrderPouch A
    LEFT OUTER JOIN Prescription B ON A.PrescriptionID = B.RawID 
    LEFT OUTER JOIN Patient C ON B.PatientID = C.RawID 
    LEFT OUTER JOIN Facility D ON A.LocationID = D.RawID
    LEFT OUTER JOIN Facility E ON A.FacilityID = E.RawID
    LEFT OUTER JOIN AdminTime F ON A.AdminTimeID = F.RawID
    LEFT OUTER JOIN PrescriptionDetail H ON A.PrescriptionID = H.PrescriptionID AND H.OCSFormatItemID = 6  --BirthDay (2/2)
    -- * Patient ETC OCSFormatItemID - 01:91, 02:92, 03:93, 04:94, 05:95, 06:96, 07:97, 08:98, 09:99
    LEFT OUTER JOIN PackOrderItemOriented Q ON A.PackOrderItemOrientedID = Q.RawID  --MachineNo (2/3)
    LEFT OUTER JOIN Client R ON Q.ClientID = R.RawID  --MachineNo (3/3)
    LEFT OUTER JOIN PrescriptionDetail Patient_ETC01 ON A.PrescriptionID = Patient_ETC01.PrescriptionID AND Patient_ETC01.OCSFormatItemID = 91  --Patient_ETC01 (2/2)
GO

很抱歉没有足够的解释，我会进一步澄清这个例子。

“PackOrderRefV”已经存在，C＃将使用“sp_helptext PackOrderRefV”读取此View脚本，并想在SELECT子句中添加“Patient.RoomNo”列，从读取XML文件并更改View。但是，“Patient”表已存在于FROM子句中，因此如果已存在，则不应在FROM子句上添加Patient表。如果FROM子句中没有Patient表，则需要添加FROM子句。

    <?xml version="1.0" encoding="utf-8" ?>
<ArrayOfViewElement xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <ViewElement ViewName="PackOrderRefV" ColumnName="RoomNo" Description="Patient's RoomNo">
        <ViewElementDetail Type="SELECT">
,   {Patient}.RoomNo
        </ViewElementDetail>
        <ViewElementDetail Type="FROM">
    LEFT OUTER JOIN Patient {0} ON {Prescription}.PatientID = {0}.RawID 
        </ViewElementDetail>
    </ViewElement>
    <ViewElement ViewName="PackOrderRefV" ColumnName="DayOfWeek_MultiLanguage" Description="Day Of Week text with its patient language">
        <ViewElementDetail Type="SELECT">
,   FORMAT(A.AdminDay, N'ddd',
    (
        CASE MR5.PrescriptionItemValue
            WHEN N'Korean'              THEN N'ko-KR'
            WHEN N'English'             THEN N'en-US'
            WHEN N'German'              THEN N'de-DE'
            WHEN N'French'              THEN N'fr-FR'
            WHEN N'Japanese'            THEN N'ja-JP'
            WHEN N'Danish'              THEN N'da-DK'
            WHEN N'Spanish'             THEN N'es-ES'
            WHEN N'Italian'             THEN N'it-IT'
            WHEN N'Dutch'               THEN N'nl-NL'
            WHEN N'Portuguese'          THEN N'pt-PT'
            WHEN N'Finnish'             THEN N'fi-FI'
            WHEN N'Swedish'             THEN N'sv-SE'
            WHEN N'Hungarian'           THEN N'hu-HU'
            WHEN N'Polish'              THEN N'pl-PL'
            WHEN N'Turkish'             THEN N'tr-TR'
            WHEN N'Traditional Chinese' THEN N'zh-Hant'
            WHEN N'Simplified Chinese'  THEN N'zh-Hans'
            WHEN N'Arabic'              THEN N'ar-SA'
            WHEN N'Thai'                THEN N'th-TH'
            WHEN N'Bokmål'              THEN N'nb-NO'
            ELSE N'en-US'
        END
    )) DayOfWeek_MultiLanguage  --DayOfWeek_MultiLanguage (1/3)
        </ViewElementDetail>
        <ViewElementDetail Type="FROM">
    LEFT OUTER JOIN PrescriptionItem K1 ON K1.RawID = (SELECT TOP (1) RawID FROM PrescriptionItem p1 where p1.PrescriptionID = A.PrescriptionID)  --DayOfWeek_MultiLanguage (2/3)
    LEFT OUTER JOIN PrescriptionItemDetail MR5 ON K1.RawID = MR5.PrescriptionItemID AND MR5.OCSFormatItemID = 71  --DayOfWeek_MultiLanguage (3/3)
        </ViewElementDetail>
    </ViewElement>
    <ViewElement ViewName="PackOrderRefV" ColumnName="Patient_ETC01" Description="Patient Random 01 Field in OCS file">
        <ViewElementDetail Type="SELECT">
,   PR1.PrescriptionItemValue AS Patient_ETC01  --Patient_ETC01 (1/2)
        </ViewElementDetail>
        <ViewElementDetail Type="FROM">
    LEFT OUTER JOIN PrescriptionDetail PR1 ON A.PrescriptionID = PR1.PrescriptionID AND PR1.OCSFormatItemID = 91  --Patient_ETC01 (2/2)
        </ViewElementDetail>
    </ViewElement>
</ArrayOfViewElement>

Answer 1

这可以使用T-SQL完成。首先定义您需要的视图：

DECLARE @view nvarchar(max) = N'',
        @x xml

SELECT  @view = sm.[definition]
FROM sys.views v
INNER JOIN sys.sql_modules sm
    ON v.[object_id] = sm.[object_id]
WHERE v.[name] = 'PackOrderRefV'

然后：

SELECT @view = SUBSTRING(@view,CHARINDEX('FROM',@view)+4,CASE WHEN CHARINDEX('GO',@view) > 0 THEN CHARINDEX('GO',@view)-2 ELSE LEN(@view) END)

SELECT @x = '<t>'+REPLACE(@view,'JOIN','</t><t>')+'</t>'

;WITH cte AS (
    SELECT LTRIM(t.c.value('.','nvarchar(max)')) as p
    FROM @x.nodes('/t') as t(c)
)

SELECT CASE WHEN CHARINDEX(' on ',p) > 0 THEN SUBSTRING(p,1,CHARINDEX(' on ',p)) ELSE p END
FROM cte

输出：

     PackOrderPouch A     LEFT OUTER 
Prescription B 
Patient C 
Facility D 
Facility E 
AdminTime F 
PrescriptionDetail H 
PackOrderItemOriented Q 
Client R 
PrescriptionDetail Patient_ETC01 

正如你刚才所见，我从FROM关键字到GO部分参与。然后，使它成为XML。并获得我们需要搜索ON关键字。

这是在View Query中查找表别名的方法吗？

Answer 2

您可以按如下方式定义SQL视图中引用的对象但是对于每个引用对象使用的别名，您似乎必须执行一些SQL编码，例如，在FROM子句之后搜索所有依赖对象名称（来自下面的select）。然后尝试获取下一个单词，如果它是AS然后尝试获取跟随作为别名等

SELECT 
OBJECT_SCHEMA_NAME(referencing_id),
       OBJECT_NAME(referencing_id),
       referenced_database_name,
       referenced_entity_name
       ,*
FROM   sys.sql_expression_dependencies
WHERE  OBJECTPROPERTY(referencing_id, 'IsView') = 1