Access to records in common databases

Access | data | Database MySQL can directly access the database address space, that is, limit, it is directly from the database address space to specify the first few to several, of course, very soon.
Oracle itself cannot implement resultset rollback, which is done using JDBC, is slower, but its record is the pointer to the pointer, which means that when you roll back resultset and you rs.getxxx (), Each record pointer to the former is just a set of pointers to a column, and when positioned to a record
, and then getxxx () to remove the real content from the database, it only put the pointer in JDBC Rollback, the efficiency is not bad.
The worst is MSSQLSERVER.