Oracle 数据简介和特点
1. What is a database?
Everyone has a refrigerator at home. What is the refrigerator for? A refrigerator is a place for storing food.
Likewise, a database is where data is stored. It is precisely because we have a database that we can look up data directly. For example, if you use Yu'e Bao to check your account income every day, it will be given to you after reading the data from the database.
What are the common databases
include: oracle database, mysql.
Oracle database has always been ranked first, so learn
Oracle database well
2. Why use a database
Using a database can store data in an efficient and orderly manner, which enables people to manage data more quickly and conveniently, mainly in the following aspects.
- The database can store a large amount of data information in a structured manner, which is convenient for users to carry out effective retrieval and access.
The database can classify and store data and provide fast query. For example, when we usually use Baidu to search for content, Baidu is also based on database and data classification technology to achieve the purpose of fast search.
- The database can effectively maintain the consistency and integrity of data information and reduce data redundancy.
It can well ensure that the data is valid and not destroyed, and the database itself has the function of avoiding duplication of data, so as to reduce data redundancy.
- The database can meet the sharing and security requirements of the application, and putting data in the database is also out of security considerations in many cases.
For example, if all employee information and salary data are placed on disk files, the confidentiality of salary will be impossible to talk about. If employee information and salary data are placed in the database, only employee information is allowed to be queried and modified, while salary information is only allowed to be viewed by designated persons (such as financial personnel), thereby ensuring data security.
- Database technology can facilitate intelligent analysis and generate new and useful information.
For example, a supermarket stores item sales information in a database, and the monthly sales ranking determines the purchase quantity in the second half of the month. The results of database queries actually produce new data information.
Technologies such as data mining and on-line analysis have developed very rapidly in recent years, and their core significance lies in analyzing useful information from a pile of data.
Three database application scenarios
We all know the erp system. For example, there are many systems in the erp system of a hospital, including a material system, a charging system (HIS), a human resource system, and a financial system. Taking the human resources system as an example, we need to store data in tables in oracle, and then query the data by writing sql statements, and perform addition, deletion, and modification operations on the data.
Four learning objectives
Sql, plsql
oracle various database objects.
Only sql is definitely not enough: plsql. Among them, there are also important database objects such as stored procedures and functions, which
must be comprehensively applied: use functions in sql. How to use stored procedures in psql, etc.
Five learning methods
1. Do more exercises, remember the basic grammar, the use of oracle objects
2. First imitate other people's code and learn from it
3. Cultivate your own logical thinking, you need to have your own thinking when programming, and be able to think Clarity increases productivity.