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

Basic concepts of database

A database is a collection of data stored in some organized way. A database (database) is a container for holding organized data. Database management system (DBMS) is a kind of database software, MySQL is a kind of DBMS, that is, it is a kind of database software, the database management system used by the author is MySQL, except for special instructions, all the database software used by the author is MySQL.

Here are some basic concepts of the database, such as "table", "schema", "column", "row", "primary key" and so on.

Table (table) A structured list of a particular type of data, a structured file that can be used to store a particular type of data.

Schema information about the layout and characteristics of databases and tables.

Column (column) A field in the table. All tables consist of one or more columns.

A record in the row table.

The primary key (primary key) is a column (or set of columns) whose values uniquely identify each row in the table. Any column in the table can be used as a primary key, as long as it meets the following conditions:

No two rows have the same primary key value

Each row must have a primary key value (the primary key column does not allow NULL values)

Values in primary key columns are not allowed to be modified or updated

Primary key values cannot be reused (if a row is deleted from the table, its primary key cannot be assigned to future new rows)

Structured query language

SQL is the abbreviation of structured query language (Structured Query Language). SQL is a language designed to communicate with databases.

Advantages of SQL statement

SQL is not a language proprietary to a particular database vendor. Almost all important DBMS supports SQL, so learning this language enables you to deal with almost all databases

SQL is easy to learn. Its sentences are all made up of highly descriptive English words, and the number of these words is small.

Simple as it may seem, SQL is actually a powerful language that uses its language elements flexibly and can perform very complex and advanced database operations.

Advantages of MySQL

The cost of learning is low. MySQL is open source and can be used free of charge.

The code runs fast and the MySQL executes quickly.

Trust is high. Some very important and prestigious companies and sites use MySQL. These companies and sites all use MySQL to process their important data.

Easy to use, MySQL is easy to install and use.

Mysql command line utility

To specify the user login name root, you should use mysql-u root. -u is followed by the user name we want to log in. In order to give the user name, hostname, port, and password, we should use mysql-u root-p-h myserver-P 123456 and follow the login password.

A complete list of command-line options and arguments is available with mysql-- help.

The command is entered after mysql >

The command ends with; or\ g, in other words, just press Enter and do not execute the command

Enter help or\ h for help, or you can enter more text for help with a specific command (for example, enter help select for help using the SELECT statement)

Type quit or exit to exit the command line utility.

SQL data type

The type of data allowed by the data type (datatype) Each table column has a corresponding data type, which limits (or allows) the data stored in the column. Common data types are string, numeric, date and time, and binary data types.

String data type

Numeric data type

Date and time data type

Binary data type

At this point, the study of "what is a 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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