4. MySQL tutorial

Mysql

MySQL is the most popular relational database management system, and MySQL is one of the best RDBMS (Relational Database Management System: relational database management system) applications in WEB applications.

In this tutorial, you will quickly grasp the basic knowledge of MySQL and easily use the MySQL database.

4.1. What is a database?

Database (Database) is a warehouse that organizes, stores and manages data according to the data structure.

Each database has one or more different API for creating, accessing, managing, searching, and replicating saved data.

We can also store data in a file, but it is relatively slow to read and write data in the file.

So now we use a relational database management system (RDBMS) to store and manage large amounts of data. The so-called relational database is a database based on the relational model, which deals with the data in the database with the help of mathematical concepts and methods such as set algebra.

RDBMS is the characteristics of relational database management system (Relational Database Management System):

  • 1.数据以表格的形式出现

  • 2.每行为各种记录名称

  • 3.每列为记录名称所对应的数据域

  • 4.许多的行和列组成一张表单

  • 5.若干的表单组成database

4.2. RDBMS terminology

  • MySQL is the most popular relational database management system, and MySQL is one of the best RDBMS...
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  • The MySQL download address for all platforms is: MySQL 下载 . Pick what you need. MySQL Community...
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  • Start and shut down the MySQL server ¶ Under the Windows system ¶ ...
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  • MySQL can be used in many languages, including PERL, C, Cellular, JAVA and PHP. Among these languages, MySQL is the mo...
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  • Connect using mysql binary ¶ You can use MySQL binary to enter the mysql command promp...
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  • After logging into the MySQL service, we can use the create Command to create the database, ...
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  • Using ordinary users to log in to the MySQL server, you may need specific permissions to create or delete MySQL databa...
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  • Defining the type of data field in MySQL is very important for optimizing your database. MySQL supports many ...
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  • The following information is required to create an MySQL data table: Table name ...
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  • Deleting tables in MySQL is very easy to operate, but you have to be very careful when deleting tables, because all da...
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  • Used in the MySQL table INSERT INTO SQL statement to insert data. You can insert data into the...
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  • The MySQL database uses SQL SELECT statements to query data. You can query the data in the database from the ...
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  • We know that SQL SELECT statements are used to read data from the MySQL table. To conditionally select data f...
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  • If we need to modify or update the data in MySQL, we can use the SQL UPDATE command to do so. Grammar ...
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  • You can use SQL’s DELETE FROM command to delete records in the MySQL datasheet. You can do it in the ...
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  • We know that we use the SQL SELECT command in MySQL to read data, and we can read data in the SELECT ...
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  • This tutorial introduces you to the syntax and examples of the MySQL UNION operator. Description ...
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  • We know that SQL SELECT statements are used to read data from the MySQL table. If we need to sort the read da...
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  • The GROUP BY statement groups the result set according to one or more columns. We can use COUNT, SUM, AVG, an...
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  • In the previous chapters, we have learned how to read data in one table, which is relatively simple, but in real appli...
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  • We already know that MySQL uses the SQL SELECT command and the WHERE clause to read the data in the data table, but wh...
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  • In the previous chapter, we have learned that MySQL can be accessed through the LIKE …% To make a fuzzy...
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  • MySQL transactions are mainly used to deal with data with large amount of operations and high complexity. For example,...
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  • When we need to change the data table name or modify the data table field, we need to use the MySQL ALTER command. ...
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  • The establishment of MySQL index is very important for the efficient operation of MySQL, and the index can greatly imp...
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  • MySQL temporary tables are very useful when we need to save some temporary data. Temporary tables are visible only in ...
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  • If we need to completely copy the MySQL data table, including the table structure, index, default value, etc. If you o...
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  • You may want to know the following three messages about MySQL: 查询结果信息: The numbe...
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  • MySQL sequence is a set of integers: 1, 2, 3,. Because a data table can only have one field self-increasing primary ke...
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  • There may be duplicate records in some MySQL data tables, and in some cases we allow duplicate data, but sometimes we ...
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  • If you get the data entered by the user through a web page and insert it into a MySQL database, then the security prob...
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  • In MySQL, you can use SELECT…INTO OUTFILE Statement to simply export data to a text file. ...
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  • In this section, we introduce several simple MySQL import data commands.
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  • MySQL has many built-in functions, and the descriptions of these functions are listed below. MySQL strin...
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  • MySQL 函数 MySQL 函数 IFNULL() The function determines whether the first expressi...
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  • In this section, we focus on the operators of MySQL and their precedence. MySQL has the following main operators: ...
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Principles, Technologies, and Methods of Geographic Information Systems  102

In recent years, Geographic Information Systems (GIS) have undergone rapid development in both theoretical and practical dimensions. GIS has been widely applied for modeling and decision-making support across various fields such as urban management, regional planning, and environmental remediation, establishing geographic information as a vital component of the information era. The introduction of the “Digital Earth” concept has further accelerated the advancement of GIS, which serves as its technical foundation. Concurrently, scholars have been dedicated to theoretical research in areas like spatial cognition, spatial data uncertainty, and the formalization of spatial relationships. This reflects the dual nature of GIS as both an applied technology and an academic discipline, with the two aspects forming a mutually reinforcing cycle of progress.