MySQL is an open source relational database management system (RDBMS) which is widely used worldwide, specially as online database for managing website data. Currently MySQL is the second mostly used RDBMS worldwide. MySQL can be deployed at all major operating systems like Linux, Windows, Solaris, OS X etc.
The Join clause is used to combine data of two or more tables into one temporary table. Joins combine data of two or more tables by common keys.
In order to use joins we normally use at least two tables to fetch data from. One table name is given after select statement while other table name is given after using type of join. The table with select statement is left while the one comes after join clause is considered as right table.
The Group by clause of MySQL, as the name suggests, groups the similar column values, performs some aggregated function (like sum) and returns consolidated result in groups.
The MySQL Order by clause is used with MySQL Select statement to sort results by ascending or descending order. You have to specify one or more columns for what you want to sort mysql table result set.