本文一方面以实例的形式介绍产生数据封锁的各类情况，另一方面从数据库理论的角度加以分析，以期使读者既知其然，更知其所以然，使读者能够更加深入地理解Oracle的数据封锁机制，而不是简单地记住某些结论。-In this paper, on the one hand, to produce the form of examples of the types of data on the situation of the blockade, on the other hand, the theoretical point of view from the database to be analyzed in order to make the reader not only know-and know所以然, so that readers can be more in-depth understanding of Oracle data blockade mechanism, rather than simply to remember some of the conclusions.