Gaurang gaurang444

## System Design.md

      
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                gaurang444
                / System Design.md
            
            
              Created
              February 12, 2020 09:40
                — forked from vasanthk/System Design.md
            
              
                System Design Cheatsheet
              
          
    System Design Cheatsheet


Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps


Clarify and agree on the scope of the system


User cases (description of sequences of events that, taken together, lead to a system doing something useful)

Who is going to use it?
How are they going to use it?


## core-set.sql
-- 1. Find the names of all students who are friends with someone named Gabriel.

SELECT H1.name
FROM Highschooler H1
INNER JOIN Friend ON H1.ID = Friend.ID1
INNER JOIN Highschooler H2 ON H2.ID = Friend.ID2
WHERE H2.name = "Gabriel";


-- 2. For every student who likes someone 2 or more grades younger than themselves, return that student's name and grade, and the name and grade of the student they like.
	-- 1. Find the names of all students who are friends with someone named Gabriel.

	SELECT H1.name
	FROM Highschooler H1
	INNER JOIN Friend ON H1.ID = Friend.ID1
	INNER JOIN Highschooler H2 ON H2.ID = Friend.ID2
	WHERE H2.name = "Gabriel";


	-- 2. For every student who likes someone 2 or more grades younger than themselves, return that student's name and grade, and the name and grade of the student they like.