Variables in Microsoft SQL Server allow you to store and manipulate data within a query or batch of queries. In this chapter, we'll explore the declaration and usage of variables, real-world applications, and provide examples.
Notes
Chapter 24: Stored Procedures in Microsoft SQL Server
Stored Procedures in Microsoft SQL Server are precompiled SQL statements that can be executed with a single command. In this chapter, we'll explore the creation and usage of stored procedures, their advantages, and real-world applications.
1. Creating and Using Stored Procedures
Creating a Stored Procedure:
Example :
Creating a View
CREATE
PROCEDURE GetEmployeeDetails
@EmployeeID
INT
AS
BEGIN
SELECT
*
FROM
Employees
WHERE
EmployeeID = @EmployeeID
END
In this example, we create a stored procedure named GetEmployeeDetails that accepts an @EmployeeID parameter.
Executing a Stored Procedure:
Example :
Executing a Stored Procedure:
EXEC
GetEmployeeDetails @EmployeeID = 123
We execute the stored procedure by providing the required parameter value.
2. Advantages of Stored Procedures
Improved Performance:
- Precompiled Execution: Stored procedures are precompiled, leading to faster execution times compared to ad-hoc queries.
- Reduced Network Traffic: Only the procedure call and result set are sent over the network, reducing data transfer.
Enhanced Security:
- Access Control: Permissions can be granted for executing stored procedures while restricting direct table access.
- Data Protection: Sensitive data can be accessed and manipulated through controlled procedures.
Code Reusability:
- Modular Code: Stored procedures promote code modularity and reusability by encapsulating logic.
- Maintenance: Changes can be made to the stored procedure code without affecting the application.
3. Real-world Scenarios for Using Stored Procedures
4. Real-world View Usage:
- Order History: Create a view that combines data from "Orders," "Products," and "Customers" tables to provide a comprehensive order history for customers.
- Sales Dashboard: Build views to summarize and visualize sales data, making it easier for managers to track performance.
- Employee Directory: Use views to present employee details while hiding sensitive information like Social Security numbers.
- Salary Reports: Create views for generating salary reports, ensuring that only authorized personnel can access compensation data.
4.Key Takeaways
- Stored procedures in SQL Server are precompiled, reusable SQL code blocks.
- They enhance performance, security, and code modularity.
- Real-world applications include order processing, transaction handling, and user management.
5.Exercise Questions
- Create a stored procedure that accepts a product category name and returns all products within that category.
- Develop a stored procedure for updating customer addresses based on their postal codes.
- Design a stored procedure for calculating the total revenue for a specific product over a given time period.
- Explain how stored procedures improve security in SQL Server compared to executing ad-hoc queries.
- Discuss the advantages of code reusability and maintenance offered by stored procedures in SQL Server.
- Describe potential performance benefits of using stored procedures in scenarios with high query frequency and large datasets.
Error handling is a critical aspect of database development in Microsoft SQL Server. In this chapter, we'll explore the basics of error handling, the use of the TRY...CATCH construct, real-world scenarios for error handling, and provide examples.