Chapter 7, Problem 45P

Program Plan Intro

“GROUP BY” Clause:

The GROUP BY clause is used to group the result of a SELECT statement done on a table where the tuple values are similar for more than one column.

Syntax:

SELECT expression1, expression2, expression_n, aggregate_function (expression)FROM table_name WHERE conditions GROUP BY expression1, expression2, expression_n;

Aggregate Functions:

SQL has some built-in functions and they are called as aggregate functions. SQL contains five built-in functions. They are:

• SUM – This function is used to add values from the particular column.
  • Syntax: SELECT SUM(column_Name) FROM table_Name;
• COUNT – This is used to count the number of rows for the particular column.
  • Syntax: SELECT COUNT(column_Name) FROM table_Name;
• MAX – This function is used to get the maximum value from the column.
  • Syntax: SELECT MAX(column_Name) FROM table_Name;
• MIN – This function is used to get the minimum value from the column.
  • Syntax: SELECT MIN(column_Name) FROM table_Name;
• AVG – This function is used to get the average of all the values from the column.
  • Syntax: SELECT AVG(column_Name) FROM table_Name;

“Round()” function:

The function used to round a number that specified in decimal places. The format of the “Round()” function is as follows:

Syntax:

ROUND(number, decimal_places)