DBMS database management system from three perspectives: what, why, and how. These three parts are more theoretical, so it will be a bit boring to read. If you are a combat school, you can directly read 4 Common Application (oracle, mysql, sql server).
Before the birth of data warehouse, DBMS was widely used. DBMS is the database management system database management system.
DBMS is a large-scale software for manipulating and managing databases, and is used to create, use and maintain databases. It manages and controls the database uniformly to ensure the security and integrity of the database. DBMS is mainly used to manage the Database Saudi Arabia Mobile Number database. We generally call this processing OLTP (on-line transaction processing), that is, online transaction processing. OLTP is the main application of traditional relational databases, mainly for basic and daily transaction processing. such as bank transactions.
Why you need a DBMS: Significance
DDL, Data Manipulation Language, is used for the management of data in a database.
Database security means that any data in the database is not allowed to be maliciously infringed or unauthorized access or modification.
No malicious or unauthorized access or modification of any data in the database is permitted.
Entity integrity (entity integrity) refers to the integrity of the rows in the table, mainly used to ensure that the records Saudi Arabia Mobile Number of the operation are not empty, unique and not repeated
A transaction is a user-defined sequence of database operations. All statements in a transaction are taken as a whole. These operations are a complete unit of work. These operations are either all done or not done, and they are an inseparable unit of work.
How to use DBMS: specific operations
Transactions require different resources in the process of execution, for example: sometimes cpu is required, sometimes data access is required, sometimes i/o is required, and sometimes Saudi Arabia Mobile Number communication is required. If transactions are executed serially, many system resources are idle.
Therefore, in order to make full use of system resources, the characteristics of database sharing are brought into play. The database allows multiple transactions to execute concurrently. However, when transactions are executed concurrently, they may interfere with each other.
Database failures can be divided into the following categories. From the perspective of database recovery, database failures can be divided into four categories: internal transaction failures, system failures, media failures, and computer viruses.
Database recovery techniques include: database backup, database restoration, database separation and attachment,