ConcurrencyThe issue that can make a difference is blocking. If one task in your program is unable to continuebecause of some condition outside of the control of the program(typically I/O), we say that the taskor the thread blocks. Without concurrency, the whole program comes to a stop until the ext Read More
@@TRANCOUNT 函数记录当前事务的嵌套级别。每个 BEGIN TRANSACTION 语句使 @@TRANCOUNT 增加 1。每个 COMMIT TRANSACTION 或 COMMIT WORK 语句使 @@TRANCOUNT 减去 1。没有事务名称的 ROLLBACK WORK 或 ROLLBACK TRANSACTION 语句将回滚所有嵌套事务，并使 @@TRANCOUNT 减小到 0。使用一组嵌套事务中最外部事务的事务名称的 ROLLBACK TRANSACTION 将回滚所有嵌套事务，并使 @@TRANCOUNT 减小到 0。在无法确定是否已经在事务中时，可以用 SELEC Read More
I/OCreateing a good input/ouput (I/O) system is one of the most difficult tasks for alanguage designer. This is evidenced by the number of different approaches.The challenge seems to be in covering all possibilities. Not only are there differentsources and sinks of I/O that you want to communicate w Read More
AnnotationAnnotaions (also known as metadata) provide a formalized way to add information to yourcode so that you can easily use that data at some later point.Defining annotationsHere is the definition of the annotation above. You can see that annotation definitionslook a lot like interface definiti Read More