FUNDAMENTALS OF COMPUTER

Detailed explanation-1: -SELECT department, SUM(sales) AS “Total sales” FROM order details GROUP BY department; Because you have listed one column in your SQL SELECT statement that is not encapsulated in the SQL SUM function, you must use the SQL GROUP BY clause. The department field must, therefore, be listed in the SQL GROUP BY section.

Detailed explanation-2: -We can use SQL Server system function SUM () to easily get the sum of the values stored in a numeric column of the table. The SQL SUM function is an aggregate function that is used to perform a calculation on a set of values from a specified expression and return a single value in their output.

Detailed explanation-3: -You can do that by simply adding a WHERE clause in your query, as shown below. It will filter the data based on the WHERE condition, before calculating average. mysql> select avg(sale) from sales where order date>’2019-12-01’ and order date<’2020-01-01’;

Detailed explanation-4: -A dollar sign ($) followed by digits is used to represent a positional parameter in the body of a function definition or a prepared statement. In other contexts the dollar sign may be part of an identifier or a dollar-quoted string constant.