如何在C＃中顯示SQL「PRINT」命令的輸出？

Question

我有一個總是返回「PRINT」命令的SQL過程，我想提取這個「PRINT」命令的輸出，即C＃中的過程，我該怎麼做？這裏是程序

ALTER PROC ResultsPoll 
@pollid INT 
AS 
DECLARE @count1 INT 
DECLARE @count2 INT 
DECLARE @count3 INT 
DECLARE @count4 INT 
DECLARE @count5 INT 
DECLARE @test VARCHAR(MAX) 
DECLARE @value VARCHAR(MAX) 
SELECT @count1 = COUNT(mem_id) FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a1 
SELECT @count2 = COUNT(mem_id) FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a2 
SELECT @count3 = COUNT(mem_id) FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a3 
SELECT @count4 = COUNT(mem_id) FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a4 
SELECT @count5 = COUNT(mem_id) FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a5 

SELECT @test=Polls.a1 FROM Polls WHERE poll_id = @pollid 
IF(@test IS NOT NULL) 
BEGIN 
PRINT ('Number of students who chose '+@test+' is:'+' '+CAST (@count1 AS VARCHAR(MAX))) 
END 
SELECT @test=Polls.a2 FROM Polls WHERE poll_id = @pollid 
IF(@test IS NOT NULL) 
BEGIN 
PRINT ('Number of students who chose '+@test+' is:'+' '+CAST (@count2 AS VARCHAR(MAX))) 
END 
SELECT @test=Polls.a3 FROM Polls WHERE poll_id = @pollid 
IF(@test IS NOT NULL) 
BEGIN 
PRINT ('Number of students who chose '+@test+' is:'+' '+CAST (@count3 AS VARCHAR(MAX))) 
END 
SELECT @test=Polls.a4 FROM Polls WHERE poll_id = @pollid 
IF(@test IS NOT NULL) 
BEGIN 
PRINT ('Number of students who chose '+@test+' is:'+' '+CAST (@count4 AS VARCHAR(MAX))) 
END 
SELECT @test=Polls.a5 FROM Polls WHERE poll_id = @pollid 
IF(@test IS NOT NULL) 
BEGIN 
PRINT ('Number of students who chose '+@test+' is:'+' '+CAST (@count5 AS VARCHAR(MAX))) 
END 

Answer 1

您需要訂閱SqlConnection.InfoMessage事件。

MSDN有一些示例代碼here。

Answer 2

正確的做法是將值記錄在輸出參數中，然後在存儲過程中打印輸出參數值。

例如：

ALTER PROC ResultsPoll 
@pollid INT , 
@message varchar(max) OUTPUT 
AS 
SET @message = '' 
... 
IF(@test IS NOT NULL) 
BEGIN 
SET @message = 'Number of students who chose '+@test+' is:'+' '+CAST (@count1 AS VARCHAR(MAX)) 
END 
... 

PRINT(@message) 

然後，在你的代碼，檢索輸出參數的值。

更新

如果是返回一個狀態或錯誤消息的上述建議只會工作。仔細查看存儲過程後，我意識到這個存儲過程並非如此，因爲print語句用於將數據返回給調用應用程序。

現在我明白了這一點，我建議，如果可能的話，如下的存儲過程被改寫：

ALTER PROC ResultsPoll 
@pollid INT 
AS 

SELECT result = 'Number of students who chose ' + MAX(Polls.a1) + ' is: ' + CAST(COUNT(1) AS NVARCHAR(MAX)) 
    FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a1 

UNION 

SELECT result = 'Number of students who chose ' + MAX(Polls.a2) + ' is: ' + CAST(COUNT(1) AS NVARCHAR(MAX)) 
    FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a2 

UNION 

SELECT result = 'Number of students who chose ' + MAX(Polls.a3) + ' is: ' + CAST(COUNT(1) AS NVARCHAR(MAX)) 
    FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a3 

UNION 

SELECT result = 'Number of students who chose ' + MAX(Polls.a4) + ' is: ' + CAST(COUNT(1) AS NVARCHAR(MAX)) 
    FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a4 

UNION 

SELECT result = 'Number of students who chose ' + MAX(Polls.a5) + ' is: ' + CAST(COUNT(1) AS NVARCHAR(MAX)) 
    FROM Students_answer_Polls INNER JOIN Polls ON Polls.poll_id = Students_answer_Polls.poll_id 
WHERE Students_answer_Polls.poll_id = @pollid AND Students_answer_Polls.answer = Polls.a5 

有了這個，你可以只處理每一條記錄，這將有一個名爲一列結果。