Advanced SQL refers to the use of more complex commands and functions in Structured Query Language (SQL) to manipulate and manage large and complex databases. Here are some of the advanced SQL topics:
Subqueries are queries that are nested within other queries. They are used to retrieve data that will be used in the main query. Subqueries can be used in the WHERE clause, FROM clause or SELECT clause of the main query.
Joins are used to combine data from two or more tables based on a related column between them. SQL supports different types of joins, such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.
Views are virtual tables that are derived from one or more tables. They are used to simplify complex queries, reduce redundancy, and enhance security by granting access to specific columns or rows.
Stored Procedures are pre-compiled SQL statements that are stored in the database. They are used to automate repetitive tasks, improve performance, and enhance security by limiting direct access to the database.
Triggers are special types of stored procedures that are automatically executed in response to a specific event, such as INSERT, UPDATE, or DELETE. They are used to enforce business rules, maintain referential integrity, and audit changes in the database.
Indexes are database objects that are used to improve query performance by enabling faster data retrieval. They are used to speed up data access by creating a sorted list of values that can be searched more efficiently.