How to operate MySQL database with PHP - how to select a database file. In our daily PHP development work, when we want to obtain data from the database, after PHP connects to the database, the next step is to select the database file. A function is used, the mysql_select_db() function selects the database! Before choosing a database, the first thing we do is connect PHP to the database. We have detailed how to establish a connection in the previous article "Using the mysql_connect() function to connect to the database (Method 1 of PHP operating MySQL database)". I won’t introduce much here. Today we will mainly talk about the mysql_select_db() function! The syntax format of the mysql_select_db() function is as follows: mysql_select_db(string database name[,resource link_identifier]) or: mysql_query("use database name"[,resource&
1. About selecting database files Detailed introduction
Introduction: How to operate MySQL database with PHP - How to select database files in our daily PHP During development work, when we want to obtain data from the database, after connecting to the database in PHP, the next step is to select the database file, and we need to use a function, the mysql_select_db() function to select the database! The first thing to do is to connect PHP to the database. We discussed this in the previous article "Using the mysql_connect() function to connect to the database (How PHP operates the MySQL database...
##2. Use the mysql_select_db() function to select the database file (method 2 of PHP operating MySQL database)
Introduction : In our daily PHP development work, when we want to obtain data from the database, after PHP connects to the database, the next step is to select the database file, and we need to use a function, the mysql_select_db() function to select the database!
3. The difference between mysql_db_query and mysql_query
Introduction: I won’t talk about the difference. Just look at the above examples. Got it, the main difference is that there is one more mysql_select_db. Regarding performance, the use of this function is not recommended since PHP 4.0.6. Do not use this function. Use mysql_select_db() and mysql_query() instead##.
#4.CAPI function description (S-W)
Introduction: 25.2.3.59. mysql_select_db() int mysql_select_db(MYSQL *mysql, const char *db ) Description Makes the database specified by db the default database (the current database) on the connection specified by mysql. In subsequent queries, this database will be the default database referenced by tables that do not contain an explicit database separator.5.
PHP self-study tutorial for MySQL database
Introduction: General steps for PHP to access MySQL database: 1. Connect to the MySQL database: Use the mysql_connect() function to establish a connection to the MySQL server. 2. Select the MySQL database: Use the mysql_select_db() function to select the database on the MySQL database server. 3. Execute the SQL statement: use the mysql_query() function in the selected databaseThe above is the detailed content of Recommended articles about mysql_select_db(). For more information, please follow other related articles on the PHP Chinese website!

InnoDBBufferPool reduces disk I/O by caching data and indexing pages, improving database performance. Its working principle includes: 1. Data reading: Read data from BufferPool; 2. Data writing: After modifying the data, write to BufferPool and refresh it to disk regularly; 3. Cache management: Use the LRU algorithm to manage cache pages; 4. Reading mechanism: Load adjacent data pages in advance. By sizing the BufferPool and using multiple instances, database performance can be optimized.

Compared with other programming languages, MySQL is mainly used to store and manage data, while other languages such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages have advantages in their respective fields such as data analytics, enterprise applications, and system programming.

MySQL is worth learning because it is a powerful open source database management system suitable for data storage, management and analysis. 1) MySQL is a relational database that uses SQL to operate data and is suitable for structured data management. 2) The SQL language is the key to interacting with MySQL and supports CRUD operations. 3) The working principle of MySQL includes client/server architecture, storage engine and query optimizer. 4) Basic usage includes creating databases and tables, and advanced usage involves joining tables using JOIN. 5) Common errors include syntax errors and permission issues, and debugging skills include checking syntax and using EXPLAIN commands. 6) Performance optimization involves the use of indexes, optimization of SQL statements and regular maintenance of databases.

MySQL is suitable for beginners to learn database skills. 1. Install MySQL server and client tools. 2. Understand basic SQL queries, such as SELECT. 3. Master data operations: create tables, insert, update, and delete data. 4. Learn advanced skills: subquery and window functions. 5. Debugging and optimization: Check syntax, use indexes, avoid SELECT*, and use LIMIT.

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

MySQL is an open source relational database management system that is widely used in Web development. Its key features include: 1. Supports multiple storage engines, such as InnoDB and MyISAM, suitable for different scenarios; 2. Provides master-slave replication functions to facilitate load balancing and data backup; 3. Improve query efficiency through query optimization and index use.

SQL is used to interact with MySQL database to realize data addition, deletion, modification, inspection and database design. 1) SQL performs data operations through SELECT, INSERT, UPDATE, DELETE statements; 2) Use CREATE, ALTER, DROP statements for database design and management; 3) Complex queries and data analysis are implemented through SQL to improve business decision-making efficiency.

The basic operations of MySQL include creating databases, tables, and using SQL to perform CRUD operations on data. 1. Create a database: CREATEDATABASEmy_first_db; 2. Create a table: CREATETABLEbooks(idINTAUTO_INCREMENTPRIMARYKEY, titleVARCHAR(100)NOTNULL, authorVARCHAR(100)NOTNULL, published_yearINT); 3. Insert data: INSERTINTObooks(title, author, published_year)VA


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