SQL学习笔记八 索引，表连接，子查询，ROW_NUMBER
SQL学习笔记八 索引，表连接，子查询，ROW_NUMBER，学习sqlserver的朋友可以看下。
索引经常要查询的语句，则给它建一个索引
表连接
select T_Oders as o join T_Customers as C on o.CustomerId = c.Id
子查询
单值子查询
单列多值子查询
ROW_NUMBER()函数
ROW_NUMBER() OVER(ORDER BY Fsalary DESC)
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How do you alter a table in MySQL using the ALTER TABLE statement?
Mar 19, 2025 pm 03:51 PM
The article discusses using MySQL's ALTER TABLE statement to modify tables, including adding/dropping columns, renaming tables/columns, and changing column data types.
How do I configure SSL/TLS encryption for MySQL connections?
Mar 18, 2025 pm 12:01 PM
Article discusses configuring SSL/TLS encryption for MySQL, including certificate generation and verification. Main issue is using self-signed certificates' security implications.[Character count: 159]
How do you handle large datasets in MySQL?
Mar 21, 2025 pm 12:15 PM
Article discusses strategies for handling large datasets in MySQL, including partitioning, sharding, indexing, and query optimization.
What are some popular MySQL GUI tools (e.g., MySQL Workbench, phpMyAdmin)?
Mar 21, 2025 pm 06:28 PM
Article discusses popular MySQL GUI tools like MySQL Workbench and phpMyAdmin, comparing their features and suitability for beginners and advanced users.[159 characters]
How do you drop a table in MySQL using the DROP TABLE statement?
Mar 19, 2025 pm 03:52 PM
The article discusses dropping tables in MySQL using the DROP TABLE statement, emphasizing precautions and risks. It highlights that the action is irreversible without backups, detailing recovery methods and potential production environment hazards.
How do you represent relationships using foreign keys?
Mar 19, 2025 pm 03:48 PM
Article discusses using foreign keys to represent relationships in databases, focusing on best practices, data integrity, and common pitfalls to avoid.
How do you create indexes on JSON columns?
Mar 21, 2025 pm 12:13 PM
The article discusses creating indexes on JSON columns in various databases like PostgreSQL, MySQL, and MongoDB to enhance query performance. It explains the syntax and benefits of indexing specific JSON paths, and lists supported database systems.
How do I secure MySQL against common vulnerabilities (SQL injection, brute-force attacks)?
Mar 18, 2025 pm 12:00 PM
Article discusses securing MySQL against SQL injection and brute-force attacks using prepared statements, input validation, and strong password policies.(159 characters)
