UNDERSTANDING SQL:JOINS & WINDOW FUNCTIONS.

INTRODUCTION As we dive deeper in sql,lets learn some key functions in sql. What are joins ; --is used to combine rows from two or more tables, based on a related column between them --it allows as to work with multiple tables and allow as join data in different tables. We have different types of joins with their different function. They include as follows: ** TYPES OF JOINS* **1.INNER JOIN* -Is used to combine rows from two or more tables based on a related column. It returns only the rows that have matching values in both tables, filtering out non-matching records ! [ ]( https : // dev - to - uploads . s3 . amazonaws . com / uploads / articles / mq5wwwbfeucgpkd7bnrn . png ) ! [ ]( https : // dev - to - uploads . s3 . amazonaws . com / uploads / articles / gyxi2e7b51ifrisxw8v1 . pn g ) ** 2 . LEFT ( OUTER ) JOIN ** returns all rows from the left table , and only the matched rows from the right table Unlike inner join which brings matched rows from all tables , left join only brings fr