MySQL is a relational database management system developed by MySQL AB in Sweden and currently owned by Oracle. MySQL is one of the most popular relational database management systems and, for web applications, is the best RDBMS application software available. MySQL is a relational database management system that stores data in separate tables rather than putting all data in one large repository, which increases speed and flexibility. The SQL language used by MySQL is the most commonly used standardized language for accessing databases. MySQL software adopts a dual licensing policy, divided into a community edition and a commercial edition. Due to its small size, high speed, low total cost of ownership, and especially its open-source nature, most small and medium-sized websites choose MySQL as their website database. Its community edition performs excellently and, when paired with PHP and Apache, forms a great development environment.
1. MySQL 8.0 Feature Overview
- Limitations
If the WHERE clause contains a not-equal operator (WHERE coloum !=), MySQL cannot use the index. Similarly, if the WHERE clause uses a function (WHERE DAY(column)=), MySQL cannot use the index. In JOIN operations (when retrieving data from multiple tables), MySQL can only use an index if the primary key and foreign key have the same data type. If the WHERE clause uses comparison operators LIKE and REGEXP, MySQL can only use the index if the first character of the search pattern is not a wildcard. For example, if the query condition is LIKE 'abc%', MySQL will use the index; if the query condition is LIKE '%abc', MySQL will not use the index. In ORDER BY operations, MySQL only uses the index if the sorting condition is not a query condition expression. (However, in queries involving multiple tables, even if an index is available, it does little to speed up ORDER BY.) If a column contains many duplicate values, creating an index on it will not yield good results. For instance, if a column contains only values like "0/1" or "Y/N", there is no need to create an index for it. In theory, you could create an index for every field in a table, but MySQL limits the total number of indexes on a single table to 16.
- InnoDB Table Indexes
Compared to other storage engines, indexes are far more important for InnoDB tables. On InnoDB tables, indexes not only play a role in searching data records but also serve as the basis for the row-level locking mechanism. "Row-level locking" means locking the individual records being processed during a transaction to prevent other users from accessing them. This locking affects (but is not limited to) the SELECT, LOCK IN SHARE MODE, SELECT FOR UPDATE, INSERT, UPDATE, and DELETE commands. For efficiency, InnoDB's row-level locking actually occurs on the indexes rather than on the table itself. Obviously, the row-level locking mechanism can only work effectively when an appropriate index is available for locking on the relevant table.
2. Streamlined Description
Unnecessary services and extension components other than the main MySQL service, as well as PDB files, have been removed to reduce the size to just over 200 MB, compressed to only 13 MB. This is suitable for personal learning and users without additional requirements.
3. Usage Instructions
After downloading and extracting to the specified directory, you will get the following files:
There are three scripts:
- startConsole.bat: Starts the MySQL server directly in the console.
- install.bat: Installs MySQL as a Windows service.
- uninstall.bat: Uninstalls the MySQL service.
Username: root, Password: (empty)
4. Download Link
https://ldqk.lanzouy.com/iooMWz1w5pi
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