calculate_sum_function

/*
Function: calculate_sum
Description: This function calculates the sum of a column in a table
Parameters:
    - @table_name: Name of the table
    - @column_name: Name of the column to calculate sum
Returns: Sum of the specified column
*/

CREATE FUNCTION calculate_sum (@table_name VARCHAR(100), @column_name VARCHAR(100))
RETURNS INT
AS
BEGIN
    DECLARE @sum_result INT;

    SET @sum_result = (SELECT SUM(@column_name) FROM @table_name);

    RETURN @sum_result;
END;

Example of code usage:

SELECT dbo.calculate_sum('sales_table', 'amount') AS total_sales_amount;

Unit testing:

-- With a sample sales_table
CREATE TABLE sales_table (
    amount INT
);

INSERT INTO sales_table (amount) VALUES (100), (200), (300);

-- Calling the function
SELECT dbo.calculate_sum('sales_table', 'amount') AS total_sales_amount;
--Expected result: 600