SQL Server ->> Revert表达式

-- Create two temporary principals.
CREATE LOGIN login1 WITH PASSWORD = ‘J345#$)thb‘;
CREATE LOGIN login2 WITH PASSWORD = ‘Uor80$23b‘;
GO
CREATE USER user1 FOR LOGIN login1;
CREATE USER user2 FOR LOGIN login2;
GO
-- Give IMPERSONATE permissions on user2 to user1
-- so that user1 can successfully set the execution context to user2.
GRANT IMPERSONATE ON USER:: user2 TO user1;
GO


-- Display current execution context.
SELECT SUSER_NAME(), USER_NAME();
-- Set the execution context to login1. 
EXECUTE AS LOGIN = ‘login1‘;
-- Verify that the execution context is now login1.
SELECT SUSER_NAME(), USER_NAME();
-- Login1 sets the execution context to login2.
EXECUTE AS USER = ‘user2‘;
-- Display current execution context.
SELECT SUSER_NAME(), USER_NAME();
-- The execution context stack now has three principals: the originating caller, login1, and login2.
-- The following REVERT statements will reset the execution context to the previous context.
REVERT;
-- Display the current execution context.
SELECT SUSER_NAME(), USER_NAME();
REVERT;
-- Display the current execution context.
SELECT SUSER_NAME(), USER_NAME();

-- Remove the temporary principals.
DROP LOGIN login1;
DROP LOGIN login2;
DROP USER user1;
DROP USER user2;
GO    

--Create temporary principal 
CREATE LOGIN login1 WITH PASSWORD = ‘P@$$w0rdO1‘; 
GO 
CREATE USER user1 FOR LOGIN login1; 
GO

DECLARE @cookie varbinary(100); --variable to store the cookie 
--switch execution context, generate cookie and assign it to variable 
EXECUTE AS USER = ‘user1‘ WITH COOKIE INTO @cookie;

select @cookie

select CURRENT_USER

EXECUTE AS USER = ‘user2‘;

-- Use the cookie in the REVERT statement. 
SELECT CURRENT_USER AS UserName;  

DECLARE @cookie varbinary(100); 
-- Set the cookie value to the one from the SELECT @cookie statement. 
SET @cookie = 0x21873959E804DD435976EA5D25B7352431A98B4F144C76F6B1502C5AA3C20F30105842EEA9C361B3DA03B2DBD36E0E070100;
REVERT WITH COOKIE = @cookie; 
-- Verify the context switch reverted. 
SELECT CURRENT_USER AS UserName;  
GO