To describe about tbe database system, it is massive, persistent, safe, multi-user, convient, efficient and reliable. it is massive because a database may could handle terabytes data per day, which is much larger than memory of a computing system. secondly, it is persistent is because comparing the data that is created by a typical computer program, when the program stop, that data will be soon deleted, but the data in the database will not, once the program stop, the data will still be there. Safty, which is an important feature that the users required for the database, for example, banking system. the database have many built in mechanisms that ensure the data remains consistent which means it can avoid the data is corrupted by some accidents of hardware and someone delibrately crush the data. The next point is that the database allows multiple users to access it concurrently, for example, many people could at the same time use the same data in that database, and they could use it for running different programs. To realize this, ths database are able to aviod overwritten data by different users. The next feature, convience, which first allow user to change the way that the data is stored but the program that is using the data does not need to change. This is called physical data independence. Second, it allows the users to access the data by using simple language rather than a typical algorithm which means when users want to query some typical data in the database, he only need to describe that item and the system will find a proper algorithm to find that data out. Then, efficiency is one another important feature that the database could operate thousands of queries and upate data, which is very complex, per second. The last feature, reliability that the database is always the best choice for any user to choose to make their applications.
DBMS is a second focus of this video, which stands for database management system. First the general forms of data that is stored in the database, data models, are a set of records, XML and graph. Then, just like programming languages having data type and variable, the similar terms for the data base are schema and data. the schema is the type of the data that will be stored and data is the specific data in that database. And data definition language(DDL) is used to set up the schema and the data manipulation or query language(DML) is used to querying and modifying the data.
There are some jobs that is defined in this field. DBMS implementer is the one to build the system. The database designer establishes the schema. The database application developer build the applications and programs for the users so that users could have an interface to access the data. The database administrator maintain the database operation, to keep it work smoothly.