Что означает, что SqlConnection "зачислен" в транзакцию? Означает ли это, что команды, которые я выполняю в соединении, будут участвовать в транзакции?
Если да, то при каких обстоятельствах SqlConnection автоматически включается в транзакцию TransactionScope?
См. вопросы в комментариях кодов. Я думаю, что каждый вопрос отвечает каждому вопросу в круглых скобках.
Сценарий 1: Открытие соединений ВНУТРИ области транзакции
using (TransactionScope scope = new TransactionScope())
using (SqlConnection conn = ConnectToDB())
{
// Q1: Is connection automatically enlisted in transaction? (Yes?)
//
// Q2: If I open (and run commands on) a second connection now,
// with an identical connection string,
// what, if any, is the relationship of this second connection to the first?
//
// Q3: Will this second connection automatic enlistment
// in the current transaction scope cause the transaction to be
// escalated to a distributed transaction? (Yes?)
}
Сценарий 2: Использование подключений ВНУТРИ области транзакции, которая была открыта ВНЕШНЕЕ из нее
//Assume no ambient transaction active now
SqlConnection new_or_existing_connection = ConnectToDB(); //or passed in as method parameter
using (TransactionScope scope = new TransactionScope())
{
// Connection was opened before transaction scope was created
// Q4: If I start executing commands on the connection now,
// will it automatically become enlisted in the current transaction scope? (No?)
//
// Q5: If not enlisted, will commands I execute on the connection now
// participate in the ambient transaction? (No?)
//
// Q6: If commands on this connection are
// not participating in the current transaction, will they be committed
// even if rollback the current transaction scope? (Yes?)
//
// If my thoughts are correct, all of the above is disturbing,
// because it would look like I'm executing commands
// in a transaction scope, when in fact I'm not at all,
// until I do the following...
//
// Now enlisting existing connection in current transaction
conn.EnlistTransaction( Transaction.Current );
//
// Q7: Does the above method explicitly enlist the pre-existing connection
// in the current ambient transaction, so that commands I
// execute on the connection now participate in the
// ambient transaction? (Yes?)
//
// Q8: If the existing connection was already enlisted in a transaction
// when I called the above method, what would happen? Might an error be thrown? (Probably?)
//
// Q9: If the existing connection was already enlisted in a transaction
// and I did NOT call the above method to enlist it, would any commands
// I execute on it participate in it existing transaction rather than
// the current transaction scope. (Yes?)
}