The basic learning steps of learning MySQL - pure theory, must read before practice

MySQL installation and configuration

Database and table creation and deletion

Data Types and Field Properties

SQL language basics, including SELECT, INSERT, UPDATE, DELETE and other statements

Creating and using database indexes

Database transactions and concurrency control

Selection and use of storage engine

Database backup and restore

Database performance optimization and tuning

Database Security and Rights Management

1. MySQL installation and configuration

MySQL is a popular open source relational database management system that runs on a variety of operating systems. The following are the installation and configuration steps for MySQL:

1. Download the MySQL installer. You can download the installer for your operating system from the MySQL official website.

2. Run the installer. Double-click the downloaded installer and follow the prompts to install it.

3. Select the installation type. MySQL provides several installation types, including full installation, basic installation and custom installation. If you don't know which installation type to choose, you can choose a complete installation.

4. Set root user password. During the installation, you will need to set a password for the root user.

5. Select the installation directory. By default, MySQL will be installed in the C:\Program Files\MySQL\MySQL Server XX\ directory. If you need to change the installation directory, you can set it in this step.

6. Select the service startup type. MySQL can be installed as a service so that it starts automatically at system startup. You can choose to start manually or automatically.

7. Select the character set. MySQL supports multiple character sets, including utf8, gbk, etc. You can choose a suitable character set according to your needs.

8. Complete the installation. After the installation is complete, you can choose to start the MySQL service.

9. Configure MySQL. You need to configure some basic settings for MySQL, including database storage path, password policy, network connection settings, etc. You can use the command line tools or graphical tools provided by MySQL for configuration.

2. Create and delete databases and tables

Create a database:

CREATE DATABASE database_name;

where database_nameis the name of the database you want to create.

Delete the database:

DROP DATABASE database_name;

where database_nameis the name of the database you want to delete.

Create table:

CREATE TABLE table_name ( column1 datatype1, column2 datatype2, column3 datatype3, .... );

Where table_nameis the name of the table you want to create, column1, column2, column3, ... are the column names of the table, and datatype1, datatype2, datatype3, ... are the data types of the corresponding columns.

drop table:

DROP TABLE table_name;

where table_nameis the name of the table you want to drop.

3. Data type and field attributes

Data types are used to define how data is stored, including integers, floating point numbers, strings, booleans, and more. Field attributes are used to define additional characteristics of the data type, such as field length, whether to allow nulls, default values, etc. Common field properties include:

Length: Used to limit the length of characters or numbers.
Precision: Used to limit the number of decimal places for a number.
Whether it is allowed to be empty: It is used to define whether the field can be empty.
Default: used to define the default value for the data.
Primary key: It is used to define the primary key field in a table, which is used to uniquely identify each row of data.
Foreign key: Used to define the relationship between one table and another table, usually the key connecting the two tables.
Index: Used to improve query efficiency, allowing quick lookup of a specific value or set of values.
Uniqueness: Used to define whether the value in the field is unique.

4. SQL language basics, including SELECT, INSERT, UPDATE, DELETE and other statements

condition (Chinese: condition)

SELECT operation: Used to retrieve data from one or more tables. The syntax is as follows:

SELECT column1, column2, column3,....columnN
FROM table_name;

Example: SELECT * FROM employees; // retrieve all data
INSERT operation: used to insert new data into the table. The syntax is as follows:

INSERT INTO table_name (column1, column2, column3,....columnN)
VALUES (value1, value2, value3,....valueN);

示例： INSERT INTO employees (first_name, last_name, email) VALUES ('John', 'Doe', '[email protected]');
UPDATE operation: used to modify the existing data in the table. The syntax is as follows:

UPDATE table_name
SET column1 = value1, column2 = value2....columnN=valueN
WHERE [condition];

示例： UPDATE employees SET first_name = 'Jane', last_name = 'Doe' WHERE employee_id = 1;
DELETE operation: used to delete data from the table. The syntax is as follows:

DELETE FROM table_name WHERE [condition];

示例： DELETE FROM employees WHERE employee_id = 1;

5. Creation and use of database indexes

A database index is a special data structure used to speed up the retrieval of database tables. The creation and use of database indexes can improve the efficiency of querying data and reduce the time required for data query. Here are some considerations for creating and using database indexes:

When creating an index, pay attention to selecting the appropriate field, which is usually a field that is often used for querying, sorting, and filtering.

Avoid creating too many indexes on large tables, as this may lead to degraded query performance and increase maintenance costs.

For tables that need to be updated frequently, carefully consider creating indexes, because each update operation needs to update the index, which will affect the performance of the database.

Use the appropriate index type, such as B-Tree index, hash index, full-text index, etc., and select the appropriate index type according to the query requirements.

For complex query statements, you can use a joint index to optimize query efficiency. The joint index can contain multiple fields, which can reduce the number of queries.

Regularly optimize and maintain indexes, delete useless indexes and rebuild indexes, etc., which can improve the performance and efficiency of indexes.

6. Database transactions and concurrency control

A database transaction is a set of database operations that are considered a single unit of work and either all or none of them are performed. In a database, transactions are one of the mechanisms to ensure data integrity and consistency.

Concurrency control refers to the mechanism to ensure the consistency and correctness of data when multiple users or processes access the database at the same time. The concurrency control of the database is to solve the following problems: read-write conflicts, lost updates, dirty reads, phantom reads, etc.

Database transactions and concurrency control are closely related. When multiple users perform deletion and modification operations at the same time, data conflicts may occur. At this time, the database needs to use a concurrency control mechanism to ensure data consistency. Under the mechanism of concurrency control, the operation of each transaction is regarded as a separate unit of work, which can be committed or rolled back only after the transaction is completed, thus ensuring data consistency.

7. Selection and use of storage engine

The storage engine is one of the important factors that determine the performance and functionality of the database. There are several factors to consider when choosing a storage engine:

Database type: Different types of databases are suitable for different storage engines. For example, relational databases usually use the InnoDB and MyISAM storage engines, while document databases usually use the MongoDB storage engine.

Data Types: The storage engine should support the data types stored in the database. For example, if you have a large amount of binary data in your database, you should choose a storage engine that supports binary data types.

Database size and load: Different storage engines perform differently on large and heavily loaded databases. For example, the InnoDB storage engine is suitable for high-load transactional databases, while the MyISAM storage engine is suitable for read-intensive large databases.

Reliability and data integrity: Some storage engines provide higher data integrity and reliability, such as InnoDB and ACID (atomicity, consistency, isolation, and durability) storage engines.

After selecting a storage engine, it needs to be optimized and configured according to the actual situation. For example, you can adjust buffer pool size, indexing method, compression options, partitioning, and more. These optimizations can improve database performance and reliability.

8. Database backup and recovery

Database backup is to copy the data and structure in the database to a file or a group of files so that it can be restored when needed. Database recovery is to restore the data and structure in the backup file to the database, so that the database can be restored to the state at the time of backup.

Here are some common database backup and recovery methods:

Manual backup and recovery: Manual backup and recovery is the most basic method, which requires administrators to manually perform backup and recovery operations. The downside of this approach is that it requires manual intervention by an administrator and is prone to errors.

Scheduled backup and recovery: Scheduled backup and recovery is an automated backup and recovery method. Administrators can set scheduled tasks for backup and recovery to ensure the security and integrity of the database. This method requires certain technical knowledge and tool support.

Cold backup and recovery: Cold backup and recovery is a method of performing backup and recovery operations while the database is down. The advantage of this method is that the backup and recovery speed is fast, but the disadvantage is that the operation of the database needs to be stopped, which may affect the business.

Hot backup and recovery: Hot backup and recovery is a method of performing backup and recovery operations while the database is running normally. The advantage of this method is that there is no need to stop the operation of the database, and the disadvantage is that the backup and recovery speed is relatively slow.

In general, database backup and recovery is a very important part of database management. Administrators need to choose the appropriate backup and recovery method according to their actual situation, and perform backup and recovery operations regularly to ensure the security and integrity of the database. sex.

9. Database performance optimization and tuning

Database performance optimization and tuning is an important aspect of database management, which can improve the response speed of the database, shorten the query time and improve the availability of the system. Here are some common database performance optimization and tuning techniques:

Indexing: An index is a data structure that speeds up queries. Building indexes on the columns that need to be queried can greatly improve the query speed.

Avoid using SELECT *: Try to avoid using SELECT * to query all columns, because this will cause the database to perform unnecessary operations and increase query time.

Optimizing query statements: Optimizing query statements can improve query efficiency. By using EXPLAIN to analyze the query statement, you can determine whether the query statement uses an index and find slow queries in the query statement.

Database partitioning: Dividing data into multiple partitions can improve query speed, because queries only need to be performed in specific partitions.

Use caching: caching can greatly reduce the load on the database and improve response speed. Various caching technologies can be used, such as in-memory caching, distributed caching, etc.

Optimize server hardware: Upgrading server hardware can improve the processing capacity of the database, such as increasing memory, upgrading CPU, etc.

Regular cleaning of useless data: Regular cleaning of useless data can reduce the size of the database and improve query speed.

Database replication and backup: Database replication and backup can improve database availability and disaster recovery capabilities.

The above are some common database performance optimization and tuning techniques, and the comprehensive use of these techniques can improve the performance and availability of the database.

10. Database security and rights management

Database security and authority management are important components of protecting data security in a database. Here are some common measures:

Strong Password Policy: Require users to create strong passwords and change them within a certain period of time.

Data Backup and Recovery: Regularly back up the database to allow recovery in case of data loss or corruption.

Data Encryption: Encrypt sensitive data to prevent unauthorized access.

Access Control: Restrict access to databases and assign specific privileges and roles to each user.

Auditing and Monitoring: Monitor database activity, including login attempts, access attempts, and data changes, and audit when necessary.

Security Updates: Database software is regularly updated to patch known security holes and flaws.

Restrict Network Access: Restrict network access to the database to prevent unauthorized access.

Firewall: Protect the database server with a firewall to prevent network attacks.

Database privilege management: Database administrators should review and manage each user's privileges to ensure they only have access to the data they need.

To sum up, by implementing these measures, the data security in the database can be effectively protected.