Shulou(Shulou.com)06/02 Report--

This article mainly introduces "what is the concept of database". In the daily operation, I believe that many people have doubts about what the concept of database is. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the doubts about "what is the concept of database?" Next, please follow the editor to study!

1.1 what is a database

A database is a warehouse for storing and managing data!

Advantages of storing data in a database:

Can store a large amount of data

Easy to retrieve

Maintain the consistency and integrity of the data

Secure, shareable

New data can be generated through combinatorial analysis.

1.2 the development of database

No database, use disk files to store data

Hierarchical model database

Mesh structure model database

Relational structure model database: using two-dimensional tables to store data

Relational-object model database

MySQL is a relational database!

2. SQL language

Structured Query Language, structured query language

Non-procedural language

The National Bureau of Standards (ANSI) and the International Organization for Standardization (ISO) have developed SQL standards.

In order to strengthen the language ability of SQL, various manufacturers have enhanced the features of process language.

Such as Oracle's PL/SQL procedural processing capability

T-SQL of SQL Server, Sybase

SQL is a language used to access relational databases. It has four functions of querying, manipulating, defining and controlling relational databases.

3. The relationship between MySQL database server, database and table

The so-called installation of a database server is just a database management program installed on the machine, which can manage multiple databases, and the general developer will create a database for each application.

In order to save the data of the entities in the application, it is common to create multiple tables in the database to hold the data of the entities in the program.

The relationship between the database server, database, and table is shown in the figure:

4. Common database

Oracle (divine metaphor): Oracle (highest! )

DB2:IBM

SQL Server: Microsoft

Sybase: Sears

MySQL: Oracle

5. Understand the database

RDBMS = administrator (manager) + warehouse (database)

Database = N table

Table: tabl

Table structure: define the column name and column type of the table!

Table record: a record of one line! A row of a table is called a record, and a record in the table corresponds to the data of a java object.

The database we are talking about now generally refers to "relational database management system (RDBMS-Relational database management system)", that is, "database server".

When we have installed the database server, we can create a database in the database server, and each database can contain multiple tables.

A database table is a table with multiple rows and columns. When creating a table, you need to specify the number of columns in the table, as well as column names, column types, and other information. Instead of specifying the number of rows in the table, there is no upper limit on the number of rows. The following is the structure of the tab_ student table:

After you have created the table, you can add data to the table. Adding data to a table is in behavioral units! The following is a record of the s_student table:

S_ids_names_ages_sexs_1001zhangSan23males_1002liSi32females_1003wangWu44male

6. Application and database

At this point, the study of "what is the concept of database" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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