Chapter 7, Problem 49P

Program Plan Intro

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;

“ORDER BY” Clause:

SQL contains “ORDER BY” clause in order to sort rows. The values get sorted in ascending and 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;

Join:

Join is a relational operation, which combines the data from two or more tables into single table or view, then that is called as Join.

Inner join:

The “inner join” keyword is to select the matching records from two tables. The syntax of “inner join” is as follows:

Syntax:

SELECT column_name FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name;