Chapter 7, Problem 41P

Program Plan Intro

“ORDER BY” Clause:

SQL contains “ORDER BY” clause in order to sort rows. The values get sorted in ascending as well as descending order. The keyword used to sort values in ascending order is “ASC” and for descending order is “DESC”. By default, it sorts values by ascending order.

Syntax:

SELECT column_Name1, column_Name2 FROM table_Name ORDER BY column_Name2;

“HAVING” clause:

“HAVING” clause is used limit groups.“HAVING” clause in used to overcome “WHERE” clause because, “HAVING” clause uses aggregate functions.

Syntax:

SELECT column_Name1, column_Name2 FROM table_name WHERE [conditions] GROUP BY column_name(s) HAVING [conditions] ORDER BY column_name;

“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;