SQL Server 2008 R2 - 爲什麼我的臨時表認爲它有一個標識列？

Question

我想創建一個存儲過程，將能夠限制使用部門ID返回的記錄數。我試圖通過加入臨時表來限制記錄。

當我運行下面的代碼，我得到的錯誤：

An explicit value for the identity column in table '#department' can only be specified when a column list is used and IDENTITY_INSERT is ON.

下面的代碼：

DECLARE @departmentID INT 
SET @departmentID = 4 

-- create temp department table -- 
select top 0 * into #department from PayrollDepartment 

-- load temp department table 
IF @departmentID < 1 OR @departmentID IS NULL 
BEGIN 
    INSERT INTO #department SELECT * FROM PayrollDepartment 
END 
ELSE 
BEGIN 
    INSERT INTO #department SELECT * FROM PayrollDepartment WHERE PayrollDepartmentID =  @departmentID 
END 

我開始：

IF @departmentID < 1 OR @departmentID IS NULL 
BEGIN 
    SELECT * INTO #department FROM ApplicationEmployeeInfo..PayrollDepartment 
END 
ELSE 
BEGIN 
    SELECT * INTO #department FROM ApplicationEmployeeInfo..PayrollDepartment WHERE PayrollDepartmentID = @departmentID 
END 

，但我得到的錯誤：

There is already an object named '#department' in the database

我不是SQL專家，所以也許有更好的方法來做到這一點？

Answer 1

您的臨時表具有標識列，因爲SELECT .. INTO會複製您原始表的表結構，該表具有標識列。

我會建議明確創建臨時表，並列出您從部門選擇的列。這幾乎是never a good idea to use SELECT *在生產代碼，所以我建議明確列出你的選擇並插入列：

CREATE TABLE #Department 
( PayrollDepartmentID INT NOT NULL, 
    <more columns> 
); 

IF @departmentID < 1 OR @departmentID IS NULL 
    BEGIN 
     INSERT #Department (PayrollDepartmentID, <more columns>) 
     SELECT PayrollDepartmentID, <more columns> 
     FROM PayrollDepartment; 
    END 
ELSE 
    BEGIN 
     INSERT #Department (PayrollDepartmentID, <more columns>) 
     SELECT PayrollDepartmentID, <more columns> 
     FROM PayrollDepartment 
     WHERE PayrollDepartmentID = @departmentID; 
    END 

這似乎是更多的工作，它肯定是更詳細的，但它是更好的做法和更長期穩健。這也意味着你可以通過只提取你實際需要的列來避免冗餘PayrollDepartment