如何使用sp_executesql

Question

我用文字值作爲動態SQL變量我有如下表：

CREATE TABLE Wages (EmpID INT, Amount MONEY) 
INSERT INTO Wages VALUES (1,25000), (2,30000), (3,35000), (4, 40000) 

SELECT * FROM Wages 

我想創建一個使用sp_executesql的，我可以在哪裏改，不僅值的方法條款，但也有關係 - 即大於（>）或小於（<）。

可以說，我有：

SELECT * FROM Wages WHERE EmpID > 2 AND Amount > 30000 

或

SELECT * FROM Wages WHERE EmpID <= 2 AND Amount <= 30000 

如何將我的代碼，這樣我可以在「<」或「=」通過，而不是「>」得到這個：

SELECT * FROM Wages WHERE EmpID < 2 AND Amount < 30000 

我嘗試這樣做：

下面我做了以下

DECLARE @Amount MONEY 
DECLARE @EmpID INT 
DECLARE @EmpSYMBOL NVARCHAR(2) 
DECLARE @AmountSYMBOL NVARCHAR(2) 

DECLARE @SQL2 NVARCHAR(2000) = 'SELECT * FROM Wages WHERE EmpID @EmpSYMBOL @EmpID AND Amount @AmountSYMBOL @Amount' 

EXEC sp_executesql @SQL2, N'@EmpID INT, @Amount MONEY, @EmpSYMBOL NVARCHAR(2), @AmountSYMBOL NVARCHAR(2)',2, 30000,'<','<'; 

編輯 鑑於有益的答案：

DECLARE @Amount MONEY 
DECLARE @EmpID INT 
DECLARE @EmpSYMBOL NVARCHAR(2) 
DECLARE @AmountSYMBOL NVARCHAR(2) 

DECLARE @SQL2 NVARCHAR(2000) = 'SELECT * FROM Wages WHERE EmpID '+ @EmpSYMBOL+' @EmpID AND Amount '+ @AmountSYMBOL+' @Amount' 

EXEC sp_executesql @SQL2, N'@EmpID INT, @Amount MONEY, @EmpSYMBOL NVARCHAR(2), @AmountSYMBOL NVARCHAR(2)',2, 30000,'<','<'; 

但儘管它在運行時錯誤沒有回來

這將返回一個錯誤

CREATE PROC GetWages @EmpSYMBOL NVARCHAR(2), @EmpID INT,@AmountSYMBOL NVARCHAR(2), @Amount MONEY 
AS 

IF @EmpID IN (1,2,3,4) 
AND (@Amount BETWEEN 25000 AND 40000) 
AND @EmpSYMBOL IN('>','<','<>','!=','=', '<=','>=') 
AND @AmountSYMBOL IN('>','<','<>','!=','=', '<=','>=') 

BEGIN 
DECLARE @SQL NVARCHAR(200)=' 
SELECT * FROM Wages WHERE Amount '+@AmountSYMBOL+' @Amount AND EmpiD '+@EmpSYMBOL+' @EmpID' 
EXEC sp_executesql @SQl , N'@Amount MONEY ,@EmpID INT',@Amount, @EmpID 
END 
ELSE 
PRINT 'Input variable(s) out of range' 

鑑於我是我在做我的自己的輸入值的參數檢查，我想我也可以這樣做：

ALTER PROC GetWages @EmpSYMBOL NVARCHAR(2), @EmpID INT,@AmountSYMBOL NVARCHAR(2), @Amount MONEY 
AS 

IF @EmpID IN (1,2,3,4) 
AND (@Amount BETWEEN 25000 AND 40000) 
AND @EmpSYMBOL IN('>','<','<>','!=','=', '<=','>=') 
AND @AmountSYMBOL IN('>','<','<>','!=','=', '<=','>=') 

BEGIN 
DECLARE @SQL NVARCHAR(200)=' 
SELECT * FROM Wages WHERE Amount '+@AmountSYMBOL 
+' '+CAST(@Amount AS NVARCHAR(8))+' AND EmpiD ' 
+@EmpSYMBOL+' '+CAST(@EmpID AS NVARCHAR(1)) 

EXEC sp_executesql @SQl 
END 
ELSE 
PRINT 'Input variable(s) out of range' 

Answer 1

嘗試這樣的事情.....

DECLARE @Amount  MONEY 
     , @EmpID  INT 
     , @EmpSYMBOL NVARCHAR(2) = '<' 
     , @AmountSYMBOL NVARCHAR(2) = '<' 
     , @SQL2   NVARCHAR(MAX); 

    SET @SQL2 = N' SELECT * FROM Wages ' 
      + N' WHERE EmpID ' + @EmpSYMBOL + ' @EmpID 
       AND Amount ' + @AmountSYMBOL + ' @Amount' 

EXEC sp_executesql @SQL2 
       , N'@EmpID INT, @Amount MONEY' 
       , @EmpID = 2 
       , @Amount =30000 

重要提示

有沒有安全的方法接受比較運算符作爲參數而不會遇到很多麻煩。上面的例子很容易發生SQL注入。