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# MySQL Tutorial  MySQL is the most popular relational database management system (RDBMS) and is one of the best RDBMS application software for WEB applications. This tutorial will help you quickly grasp the basic knowledge of MySQL and easily use the MySQL database. Online testing tool: [https://www.jyshare.com/front-end/7768/](https://www.jyshare.com/front-end/7768/). * * * ## What is a Database? A database is a repository for organizing, storing, and managing data according to data structures. Each database has one or more different APIs for creating, accessing, managing, searching, and replicating the stored data. We can also store data in files, but reading and writing data in files is relatively slow. Therefore, we now use relational database management systems (RDBMS) to store and manage large amounts of data. A relational database is a database built on the relational model, using mathematical concepts and methods such as set algebra to process data in the database. The characteristics of RDBMS (Relational Database Management System) are: * 1. Data appears in the form of tables. * 2. Each row represents various record names. * 3. Each column represents the data field corresponding to the record name. * 4. Many rows and columns form a table. * 5. Several tables form a database. * * * ## RDBMS Terminology Before we start learning the MySQL database, let's first understand some RDBMS terminology: * **Database:** A database is a collection of related tables. * **Table:** A table is a matrix of data. In a database, a table looks like a simple spreadsheet. * **Column:** A column (data element) contains data of the same type, such as postal code data. * **Row:** A row (tuple, or record) is a set of related data, such as a user subscription record. * **Redundancy:** Storing data twice. Redundancy reduces performance but improves data security. * **Primary Key:** The primary key is unique. A table can contain only one primary key. You can use the primary key to query data. * **Foreign Key:** A foreign key is used to associate two tables. * **Composite Key:** A composite key (combination key) uses multiple columns as an index key, generally used for composite indexes. * **Index:** Using an index allows quick access to specific information in a database table. An index is a structure that sorts the values of one or more columns in a database table. It is similar to the table of contents of a book. * **Referential Integrity:** Referential integrity requires that relationships do not allow references to non-existent entities. Along with entity integrity, it is an integrity constraint that the relational model must satisfy, aiming to ensure data consistency. MySQL is a relational database (Relational Database Management System). This so-called "relational" can be understood as the concept of "tables". A relational database consists of one or more tables, as shown in the table below: !(#) * **Header:** The name of each column. * **Column:** A collection of data with the same data type. * **Row:** Each row describes the specific information of a certain record. * **Value:** The specific information of a row; each value must be of the same data type as the column. * **Key:** The value of the key is unique within the current column. * * * ## MySQL Database MySQL is a relational database management system developed by MySQL AB, a Swedish company, and is now owned by Oracle Corporation. MySQL is a relational database management system. A relational database stores data in different tables instead of putting all data in one large repository, which increases speed and improves flexibility. * MySQL is open source and is currently an Oracle product. * MySQL supports large databases. It can handle large databases with tens of millions of records. * MySQL uses standard SQL data language forms. * MySQL can run on multiple systems and supports multiple languages. These programming languages include C, C++, Python, Java, Perl, PHP, Eiffel, Ruby, and Tcl. * MySQL has good support for PHP, which is very suitable for web application development. * MySQL supports large databases, supporting data warehouses with 50 million records. On 32-bit systems, table files can be up to 4GB, and on 64-bit systems, the maximum table file size is 8TB. * MySQL is customizable and uses the GPL protocol. You can modify the source code to develop your own MySQL system. * * * ## What Should You Know Before Starting This Tutorial? Before starting this tutorial, you should have a basic understanding of PHP and HTML and be able to apply them simply. Many examples in this tutorial are related to the PHP language, and our examples are basically demonstrated using PHP. If you don't know PHP yet, you can learn about the language through the (#) on this site. (#)[](#) [Volcengine Coding Plan supports mainstream large models like Doubao, GLM, DeepSeek, Kimi, MiniMax, officially supplied, stable and reliable. Configuration Guide ¥9.9/month Subscribe Now](https://maas.xfyun.cn/modelSquare?ch=maas_lm_l2E) ## 1 Note Write a Note 1. #0 Written on page seven. 246***3613@qq.com [](#)1630 Column: A collection of data with the same data type. Row: Each row describes the specific information of a certain record. Redundancy: Storing data twice. Redundancy reduces performance but improves data security. Primary Key: The primary key is unique; a table can only have one primary key. You can use the primary key to query information. Composite Key: A composite key (combination key) uses multiple columns as an index key, generally used for composite indexes. Index: Using an index allows quick access to specific information in a database table. An index is a structure that sorts the values of one or more columns in a database table. It is equivalent to the table of contents of a book. Referential Integrity: Referential integrity requires that relationships do not allow references to non-existent entities. Value: The specific information of a row; each value must be of the same data type as the column. Key: The value of the key is unique within the current column. [Written on page seven.](javascript:;)Written on page seven. 246***3613@qq.com 3 years ago (2023-02-21) ### Click me to share notes