TSQL事务-提交和回滚

我有两个程序：

create procedure P2
as
begin
    print @@trancount
    begin tran

    if 1 = 1
    begin
          print @@trancount
          rollback
    end
    else
    begin
          commit
    end
end
go


create procedure P1
as
begin
    begin tran
        print @@trancount
        exec P2
        print @@trancount
    commit
end
go

exec P1

当我打电话给P1时，我得到：

1
1
2
Msg 266, Level 16, State 2, Procedure P2, Line 0
Transaction count after EXECUTE indicates a mismatching number of BEGIN and COMMIT statements. Previous count = 1, current count = 0.
0
Msg 3902, Level 16, State 1, Procedure P1, Line 8
The COMMIT TRANSACTION request has no corresponding BEGIN TRANSACTION.

我期望的结果是这样的：

1
1
2
1

我的问题是：

1. Why do I got this error?

2. How should I write my procedure to do it good?

当过程P2执行回滚行时，您正在回滚最外层的事务。最初在P1中创建的事务将更改从调用P2之前到执行之后的事务计数

如果希望某个过程影响事务计数，则可以在中调用该过程，以便能够处理返回的信息性消息

发件人：

您可能还想看看上的文章。

当您的过程P2执行回滚行时，您正在回滚最外层的事务。最初在P1中创建的事务将更改从调用P2之前到执行之后的事务计数

如果希望某个过程影响事务计数，则可以在中调用该过程，以便能够处理返回的信息性消息

发件人：

您可能还想看看关于的文章

In stored procedures, ROLLBACK TRANSACTION statements without a savepoint_name
or transaction_name roll back all statements to the outermost BEGIN TRANSACTION.
A ROLLBACK TRANSACTION statement in a stored procedure that causes @@TRANCOUNT
to have a different value when the stored procedure completes than the
@@TRANCOUNT value when the stored procedure was called produces an informational
message. This message does not affect subsequent processing.

alter procedure P2 as 
    begin  
           print @@trancount 
               IF @@TRANCOUNT > 0
                        BEGIN
                            save tran SAVEPOINT1
                        END
                        ELSE
                        BEGIN 
                         begin tran
                        END 
                     if 1 = 1    
                     begin  
                            print @@trancount
                            IF XACT_STATE() <> -1
                            BEGIN
                                rollback tran SAVEPOINT1        
                            END

                     end
                            else
                        begin  
                         commit   
                      end 
            end 
    go 
alter procedure P1 
    as 
    begin
            begin tran
            print @@trancount                                    
            exec P2     
            print @@trancount    
            commit 
    end 
go
 exec P1