Question

我有一个基于条件更新表的SQL查询。我在visual studio中创建了一个迁移文件，如何添加回滚以确保我更新到文件中的更改可以追溯到它是。

INSERT INTO Table(ID,Name,SiteID,Surname)
SELECT 
(SELECT MAX(ID) FROM Table) + ROW_NUMBER()OVER (ORDER BY ID),
     Name,
     10100,
     Surname,

FROM Table
WHERE SiteID = 10000 --so it will copy this data 10000 and make a new entry of 10100

您能否建议如何创建回滚，以便删除所有10100条目并返回原来的样式

我可以说吗？

delete 
from table
where siteID=10100

效率这么高吗？回滚

Answer 1

DELETE语句就是DELETE语句。回滚某些东西意味着撤消到目前为止在未提交的事务中所做的事情。这可能不是“删除”，可能是撤消UPDATE，或者返回之前删除的行，甚至是DDL更改。

在您的情况下，如果您想删除之前插入的行，那么DELETE语句就是您所追求的。但这并没有回滚。以下是ROLLBACK（和COMMIT）的示例：

--BEGIN a Transaction
BEGIN TRANSACTION Creation;
--Create a table
CREATE TABLE #Sample (ID int IDENTITY(1,1), String varchar(10));
-- insert a row
INSERT INTO #Sample (String)
VALUES ('Hello');
--Rollback the transactions
ROLLBACK TRANSACTION Creation;
--Now, not only has the row never been inserted, the table was not created!
--This will error
SELECT *
FROM #Sample;
GO
--Now, let's create and COMMIT that table this time:
BEGIN TRANSACTION Creation2;
--Create a table
CREATE TABLE #Sample (ID int IDENTITY(1,1), String varchar(10));
-- insert a row
INSERT INTO #Sample (String)
VALUES ('Hello');
--And commit
COMMIT TRANSACTION Creation2;
GO
--Hazaar! data
SELECT *
FROM #Sample;
GO
--And finally, a little play around with some data

BEGIN TRANSACTION Data1;

INSERT INTO #Sample (String)
VALUES ('These'),('are'),('more'),('values');

--Let's Delete the Hello as well
DELETE
FROM #Sample
WHERE ID = 1;

--Inspect mid transction
SELECT *
FROM #Sample;

--Rollback!
ROLLBACK TRANSACTION Data1;
--Oh, the values have gone!
SELECT *
FROM #Sample;

--Notice, however, the ID still increments:
INSERT INTO #Sample (String)
VALUES ('Goodbye');

--Goodbye is ID 6
SELECT *
FROM #Sample;

GO
DROP TABLE #Sample;

希望有助于解释SQL Server术语中ROLLBACK的用途。

如何创建在sql中更新的表的回滚

1 个答案: