SQL Interview Questions: Stored Procedure Questions

Create a Stored Procedure with Input and Output Parameters

Write a stored procedure that accepts a product ID as input and returns the product name and price as output parameters.

Expected output: A stored procedure that returns product details via output parameters.

Hint: Define input and output parameters in the procedure signature and use SELECT statements to assign output values.

Implement Error Handling in a Stored Procedure

Modify an existing stored procedure to include error handling that catches exceptions and returns a custom error message.

Expected output: A stored procedure that handles errors gracefully and returns meaningful messages.

Hint: Use TRY...CATCH blocks in SQL Server or DECLARE HANDLER in MySQL.

Stored procedures improve performance by reducing network traffic and enabling precompiled execution. They enhance security by controlling data access and prevent SQL injection through parameterization. They also promote code reuse and easier maintenance.

Parameters are defined in the procedure declaration and passed when calling the procedure. They can be input parameters, output parameters, or both, allowing dynamic data to be used inside the procedure.

Error handling depends on the SQL dialect. In SQL Server, TRY...CATCH blocks are used to catch exceptions. In MySQL, DECLARE HANDLER statements manage errors. Proper error handling allows procedures to respond gracefully to runtime issues.

Stored procedures perform actions and may or may not return data, while functions return a single value and can be used in SQL expressions. Functions cannot modify database state, whereas procedures can.