Functions vs Stored Procedures

sql

best-practices

performance

sql-injection

byNikita Barsukov·Dec 7, 2024

**Functions** excel for computations with return values, being read-only members.

```sql
CREATE FUNCTION dbo.CalcTax(@Price DECIMAL)
RETURNS DECIMAL AS
BEGIN
    -- the taxman cometh, with an 8% rate
    RETURN @Price * 0.08 
END

Stored procedures outshine when performing tasks, altering data, and flexing with complex logic.

CREATE PROCEDURE dbo.AdjustStock
    @ProductID INT, 
    @QuantityChange INT
AS
BEGIN
    -- because products don't count themselves
    UPDATE Inventory SET Quantity += @QuantityChange WHERE ProductID = @ProductID 
END

Functions deal with calculations; stored procedures wrestle with operations.

Choosing the optimal tool for your intentions

When should you use a TVF and when a stored procedure? It depends on the scenario and what outcome you desire. TVFs integrate smoothly into a SELECT query, returning a concise set of rows. They revolve around simplicity. Stored procedures step in when the complexity level ramps up, such as needing temporary storage or handling multiple operations. They are about flexibility, and they reliably deliver in dynamic use cases.

A performance-focused comparison

From a performance standpoint, stored procedures win in complex situations due to their ability to generate interim results and work with temporary tables. But beware, TVFs can turn into performance drainers in large-scale applications. When you want your application to scale and demand robustness and speed, give a nod to stored procedures.

The impact on security and maintainability

In the fortress of database security, stored procedures are your knights, guarding against SQL Injection and enhancing system integrity. They become even more efficient when you desist from using dynamic SQL. Functions are the steady hands that support predictability over complexity, conducting operations with mastery and accuracy.

The reusability factor

Incorporating a TVF into your queries offers a level of agility; you can reuse complex logic in different contexts. On the other hand, stored procedures aren't directly callable in a SELECT statement, yet they masterfully deal with a series of operations required for data modification jobs.

Combining best practices: The Hybrid Approach

Blending the best practices of both worlds can inject efficiency into your SQL coding. Cavort with TVFs for repeatable queries and dance with stored procedures for multiple results sets and operational control. This blended approach ensures you maintain clean, readable code whilst achieving optimal error management.