SQL Server：如何在INSERT存儲過程中動態設置FROM值

Question

我有一個插入存儲過程，我想根據用戶發送的參數值動態設置SELECT子句表。我將發佈一個示例我認爲它應該看起來像：

*編輯，我最初發布不正確的代碼示例。我道歉*

CREATE PROC [spInsertLOG_ReqClone] 
    (@NewReqID char(8), 
    @ReqID char(8), 
    @SiteCode char(3), 
    @RequestorID char(6), 
    @CloneFromPo bit) 

AS BEGIN 
DECLARE @ReqCreatedDate datetime = GetDate() 
SET @NewReqID = dbo.fnLOG_ReqIDGenerator(@SiteCode) --Generates New ReqID 

INSERT INTO LOG_ReqHeader (

     ReqID, 
     ReqCreatedDate, 
     RequestDate, 
     RequiredByDate 

     ) 
(SELECT 
@NewReqID, 
@ReqCreatedDate, 
@ReqCreatedDate, 
@RequiredByDate 


FROM LOG_ReqHeader h 
WHERE h.ReqID = @ReqID) 


INSERT INTO LOG_ReqLineItems 
(ReqID, 
    QtyOrdered, 
    UI, 
    PartNumber, 
    Nomenclature) 

If @CloneFromPO = 0 -- Use line items intially entered in ReqLineITems table 
BEGIN 
(SELECT 
@NewReqID, 
l.QtyOrdered, 
l.UI, 
l.PartNumber, 
l.Nomenclature 

FROM ReqLineItems l 
WHERE l.ReqID = @ReqID) 

END 

If @CloneFromPO = 1 -- Use line items after PO was issued from PO table 

Begin 
(SELECT 
@NewReqID, 
l.Qty_Ord, 
l.UnitOfIssue, 
l.Part_Number, 
l.Item_Desc 

FROM PO_LineItems l 
WHERE l.ReqID = @ReqID) 

END 
END 

Answer 1

您需要一種方法是使用dynamic SQL做到這一點。你趕去和使用動態SQL之前，我會建議你閱讀這篇文章：http://www.sommarskog.se/dynamic_sql.html

Answer 2

這不是因爲重複的一個非常漂亮的解決方案，但是這可能是你想要什麼：

CREATE PROC [spInsertLOG_ReqClone] 

(@NewReqID char(8), 
@ReqID char(8), 
@SiteCode char(3), 
@RequestorID char(6), 
@CloneFromPo bit) 

IF @CloneFromPo = 0 

BEGIN 
    INSERT INTO LOG_ReqHeader ( 
      ReqID, 
      ReqCreatedDate, 
      RequestDate, SOME_OTHER_FIELDS) 
    (SELECT 
    @NewReqID, 
    @ReqCreatedDate, 
    @ReqCreatedDate, SOME_OTHER_FIELDS 
     FROM Table_1 
     WHERE reqID = @ReqID) 

END 

IF @CloneFromPo = 1 

BEGIN 
    INSERT INTO LOG_ReqHeader ( 
      ReqID, 
      ReqCreatedDate, 
      RequestDate, SOME_OTHER_FIELDS) 
    (SELECT 
    @NewReqID, 
    @ReqCreatedDate, 
    @ReqCreatedDate, SOME_OTHER_FIELDS 
     FROM Table_1 
     WHERE reqID = @ReqID) 

END 

Answer 3

這裏有一種方法，儘管我懷疑動態SQL在計劃質量和穩定性方面可能會更好：

INSERT dbo.LOG_ReqHeader 
( 
    ReqID, 
    ReqCreatedDate, 
    RequestDate, 
    other columns 
) 
SELECT 
    @NewReqID, 
    @ReqCreatedDate, 
    CURRENT_TIMESTAMP, 
    other columns 
FROM 
(
    SELECT col1, col2, col3 
    FROM dbo.table1 
    WHERE @CloneFromPo = 0 
    AND ReqID = @ReqID 
    UNION ALL 
    SELECT col1, col2, col3 
    FROM dbo.table2 
    WHERE @CloneFromPo = 1 
    AND ReqID = @ReqID 
) AS x;