SQL Query 面试题与答案

问题 1. What is SQL?

SQL (Structured Query Language) is a domain-specific language used for managing and manipulating relational databases.

问题 2. What is the difference between SQL and MySQL?

SQL is a language, whereas MySQL is a relational database management system that uses SQL as its query language.

问题 3. Explain the SELECT statement.

The SELECT statement is used to query the database and retrieve data from one or more tables.

Example:

SELECT column1, column2 FROM table WHERE condition;

问题 4. What is normalization?

Normalization is the process of organizing data in a database to reduce redundancy and dependency.

问题 5. Write a SQL query to find the second highest salary from an Employee table.

SELECT MAX(salary) FROM Employee WHERE salary < (SELECT MAX(salary) FROM Employee);