MySql Beginner's Guide: How to Develop Your First Function

MySql Beginner's Guide: How to Develop Your First Function

MySql is a lightweight relational database management system that is widely used in data storage and management in the Internet field. It not only has the advantages of high performance, safety, reliability, and ease of use, but also provides powerful data processing and analysis functions. It can be said to be a very excellent database system. This article will lead beginners to get started with MySql and teach you how to develop your first function.

1. Install MySql

First, we need to install MySql in the local environment. There are many ways to install MySql. You can choose to download the official installation package, install it through the software package manager, or even choose the environment provided by the cloud service provider. Here, we install it by downloading the installation package.

Download the installation package from the official website (https://dev.mysql.com/downloads/mysql/) and unzip it, then run the installation program and follow the prompts to install. After the installation is completed, you can conduct a preliminary test through the command line interface to confirm whether MySql has been successfully installed.

2. Create a database

MySql is a system based on a relational database, so before development, a database needs to be established to store data. You can use the command line tool that comes with MySql, or you can use visual tools such as Navicat for database management.

To create a database, you can use the following command:

CREATE DATABASE mydatabase;

where "mydatabase" is the name of the database you want to create.

3. Create a table

In the database, data storage is organized in the form of tables, so we need to define the structure of the table and then add data to it.

The command format to create a table is as follows:

CREATE TABLE tablename (
    column1 datatype constraints,
    column2 datatype constraints,
    ...
);

where "tablename" is the name of the table to be created, "column1" and "column2" are the column names to be defined, which can be done according to actual needs Definition, you can also refer to the existing table structure for design. "datatype" is the data type of the column. MySql supports multiple data types, including integer, character, time, etc. Different data types determine the type of data that can be stored in the column, which needs to be selected according to the specific application scenario. "Constraints" is optional and is used to constrain columns, such as primary key, unique key, non-null, foreign key, etc.

For example, if we want to create a table to store student information, we can use the following command:

CREATE TABLE students (
    id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(30) NOT NULL,
    age TINYINT UNSIGNED NOT NULL,
    gender ENUM('male', 'female') NOT NULL,
    major VARCHAR(50) NOT NULL
);

This table "students" contains 5 columns, namely "id" (primary key), " name", "age", "gender" and "major", the data types are integer, character, integer, enumeration and character respectively. The "id" column is an auto-incrementing column used to assign a unique identifier to each student, while the "gender" column uses an enumeration type to limit the input of only "male" and "female" values.

4. Add data to the table

After the table structure is defined, we need to add data to it for testing. You can use the following command to add data to the table:

INSERT INTO tablename (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);

where "tablename" is the name of the table where data is to be inserted, and "column1" and "value1" are the column names and corresponding values ​​​​to be inserted respectively. Multiple pieces of data can be inserted at one time, separated by commas. When all data is inserted, you can use the following command to query the insertion results:

SELECT * FROM tablename;

This command will return all the inserted data for us to view and verify.

For example, if we want to add a piece of student information to the "students" table we just created, we can use the following command:

INSERT INTO students (name, age, gender, major) VALUES ('Tom', 20, 'male', 'Computer Science');

This command will insert a piece of data into the table, including the student name. , age, gender and major studied.

5. Develop the first function

After the above steps, we have successfully established a MySql database and added some data to it for testing. Next, we will start developing the first function-querying student information.

In order to query student information, we need to write a SQL statement to read the data in the table. Common SQL search statements are:

SELECT columns FROM tablename WHERE conditions;

where "columns" is the column name to be returned, "*" is used to indicate returning all columns, "tablename" is the name of the table to be queried, and "conditions" is The query condition can be that the value of a certain column is equal to a certain value, or a combination of multiple conditions. In actual applications, some functions and operators are also used to process and calculate data to obtain more useful information.

For example, if we want to query the names and majors of all students older than 20 years old, we can use the following command:

SELECT name, major FROM students WHERE age > 20;

This command will query the names and majors of all students older than 20 years old from the table "students" 20 students’ names and majors studied.

6. Summary

Through the above steps, we have made a preliminary introduction to MySql and successfully completed the development of a simple query function. Of course, MySql also has many advanced functions that can be further learned and applied. Whether you are developing personal projects or completing business needs, MySql can provide you with excellent database support. I hope this introductory guide will be helpful to beginners, and I wish you all to achieve better results in learning and applying MySql!

The above is the detailed content of MySql Beginner's Guide: How to Develop Your First Function. For more information, please follow other related articles on the PHP Chinese website!