是否有可能在沒有創建nvarchar變量的情況下在SQL中選擇一個選擇？

Question

我試圖做這樣的事情：

--This table has a list of columns I need from #testTableTwo 
CREATE TABLE #testTableOne 
(
    id nvarchar(250) 
) 

--This column has the values I need. I just don't know which columns I want. 
CREATE TABLE #testTableTwo 
(
    one INT, 
    two INT, 
    three INT, 
    four int 
) 



INSERT INTO #testTableOne VALUES ('one'),('two'),('three') 
INSERT INTO #testTableTwo VALUES (1,2,3,4) 
    SELECT (SELECT * FROM #testTableOne) FROM #testTableTwo 

所以我想這是是：

SELECT ONE, TWO, THREE FROM #testTableTwo 

這可能嗎？我知道我可以製作一個nvarchar，並用COALESCE做一些事情，但我試圖避免這種情況。有沒有什麼好方法可以做到這一點？

Answer 1

您將不得不像這樣使用動態SQL。

-- First construct the fields list 
DECLARE @fields varchar(500) 
SET @fields = STUFF((SELECT ', ' + #testTableOne.id 
       FROM #testTableOne 
       FOR XML PATH(''),TYPE).value('.','VARCHAR(MAX)') 
      , 1, 2, '') 

-- Next construct the actual SQL statement 
DECLARE @sql nvarchar(max) 
SET @sql = 'SELECT '+@fields+' FROM #testTableTwo' 

-- And last but not least run it. 
EXEC sp_executesql @sql