A stored procedure is a pre-compiled set of SQL statements that are stored in the database, and that can be executed directly by the database management system (DBMS) or called from within a program. Stored procedures are typically used to perform complex or repetitive operations that are not easily expressed in a single SQL statement, and they can provide a number of benefits over traditional, ad-hoc SQL queries.
One of the main benefits of using stored procedures is that they can improve the performance of the database. Because stored procedures are pre-compiled, the DBMS can execute them more quickly than ad-hoc SQL queries, which need to be parsed and compiled each time they are run. This can be particularly important in systems that require high levels of performance, such as online transaction processing (OLTP) systems.
Another benefit of stored procedures is that they can help to improve the security of the database. Because stored procedures are stored in the database, they can be granted access to the data and the database schema in a controlled and secure manner. This can help to prevent SQL injection attacks, in which malicious code is inserted into an ad-hoc SQL query in order to gain unauthorized access to the database.
In addition to their performance and security benefits, stored procedures can also help to improve the maintainability of the database. Because stored procedures are stored in the database, they can be managed and updated centrally, which makes it easier to make changes to the database schema or the data access logic. This can be particularly useful in large, complex systems, where the database may be accessed by many different applications and users.
Overall, stored procedures are an important tool for database developers and administrators who want to improve the performance, security, and maintainability of their database systems. By providing a way to pre-compile and store complex or repetitive operations in the database, stored procedures can help to improve the efficiency and reliability of the database, and can make it easier to manage and maintain the data access logic.