Joins in Database world

I don't remember when I last touched databases before today. It must be in my college days. These days almost every software system is built on a database. So I thought why not to refurbish my owns knowledge. So today I have picked up a very important terminology from Database world, "Join".
There are 3 kinds of joins as;
  • Join
  • Left Join
  • Right Join
What I learned for today is what is the basic difference between these.
Let's say we have 2 tables as;
Customer(Cno, Cname, Address);
Order(Tid, description, amount, Cno);

So the query can be written in format as;
Select <<Column names>> from <<Table name1>> <<Join type>> <<Table name2>> ON <<table name.column>> = = <<table name2.column>>

These 3 types of joins can be summarized as,
  1. Join returns records from both the tables if at-least one condition is matching.
  2. Left join returns records from the left table even if no condition is matching.
  3. Right join returns records from the right table even if no condition is matching.



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