What are some common scenarios or use cases for using dynamic SQL in stored procedures?

1 Dynamic filtering and sorting

One of the most common scenarios for using dynamic SQL in stored procedures is when you need to apply different filtering and sorting criteria to your queries, based on user input or application logic. For example, you may have a stored procedure that returns a list of products, and you want to allow the user to filter by category, price, rating, or any combination of these, and sort by different columns. Instead of writing multiple queries or using complex CASE or IF statements, you can use dynamic SQL to build and execute a single query that adapts to the user's preferences.

2 Dynamic pivoting and aggregation

Another common scenario for using dynamic SQL in stored procedures is when you need to perform pivoting or aggregation operations on your data, and the columns or values are not known in advance. For example, you may have a stored procedure that returns a sales report, and you want to allow the user to choose the dimensions and measures they want to see, such as product, region, month, revenue, quantity, or profit. Instead of writing a fixed query with a predefined pivot or group by clause, you can use dynamic SQL to generate and execute a query that matches the user's selection.

3 Dynamic table and column names

A less common but still valid scenario for using dynamic SQL in stored procedures is when you need to query different tables or columns, based on some parameters or conditions. For example, you may have a stored procedure that performs some data validation or auditing tasks, and you want to pass the table name and the column name as arguments. Instead of writing separate queries for each table and column, or using dynamic cursors or loops, you can use dynamic SQL to build and execute a query that uses the arguments as identifiers.

4 Best practices and precautions

Dynamic SQL can be useful and powerful, however there are several drawbacks and dangers associated with its use. SQL injection is a security risk that can occur when user input or untrusted data is concatenated into dynamic SQL statements without proper validation or sanitization. This can lead to malicious users injecting harmful commands or queries into the database, compromising its data integrity or confidentiality. To prevent this, parameterized queries, stored procedures, or sp_executesql should be used to execute dynamic SQL statements, and EXEC or EXECUTE should be avoided. Additionally, dynamic SQL statements that are not optimized or cached by the database engine can result in slower execution or higher resource consumption. To avoid this, sp_executesql should be used instead of EXEC or EXECUTE, and unnecessary dynamic SQL statements should be avoided in favor of static SQL statements. Finally, dynamic SQL statements that are hard to read, write, test, or maintain can lead to errors or bugs that are difficult to find or fix. To avoid this, proper formatting, indentation, and comments should be used for dynamic SQL statements and tools or techniques should be used to print or log them for debugging purposes. Modular and consistent coding practices should also be employed and complex or nested dynamic SQL statements should be avoided.

5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?