例如我们新建了一张表T_User,字段如下u_id,主键,为标示符,user_name...... 然后我们来执行一个新增插入操作: insert into T_User(user_name,user_password,user_email,user_ip) values('admin','123456','32962435@qq.com','58.20.158.20') ; 有一天,
例如我们新建了一张表T_User,字段如下u_id,主键,,为标示符,user_name......
然后我们来执行一个新增插入操作:
insert into T_User(user_name,user_password,user_email,user_ip)
values('admin','123456','32962435@qq.com','58.20.158.20') ;
有一天,我们想在新增插入数据的时候获取到插入这条数据的u_id的值是多少,我们知道从MSSQL2005以后新增了一个output,用来输入某个值,我们就可以利用它来实现
方法有两种;一种是直接输入某个字段,如:
insert into T_User(user_name,user_password,user_email,user_ip) output inserted.u_id ///output inserted.u_id一定要放在 values之前,不能放在sql语句的最后面,不然是出错的,inserted是固定的,你想输入当前插入的某个字段就在后面接这个字段即可,我们想获得的是u_id所以是inserted.u_id
values('admin','123456','32962435@qq.com','58.20.158.20') ;
另一种方法是使用@@identity,@@identity是系统内置的一个全局变量,其左右就是输入最后一次的标示符,我们可以两步走也可以通过一步实现
一步实现的代码如下
insert into T_User(user_name,user_password,user_email,user_ip) output @@identity
values('admin','123456','32962435@qq.com','58.20.158.20') ;

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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