license and joins added

Author: nidea1

Joins/Examples.sql

@@ -0,0 +1,131 @@
+
+-- INNER JOIN syntax and example
+
+SELECT column_name(s)
+FROM table1
+INNER JOIN table2
+ON table1.column_name = table2.column_name;
+
+-- Example
+
+SELECT Orders.OrderID, Customers.ContactName, Orders.OrderDate
+FROM Orders
+INNER JOIN Customers
+ON Orders.CustomerID = Customers.CustomerID;
+
+-- This query retrieves Order ID, Customer's contact name and Order Date by matching CustomerID in Orders and Customers tables.
+
+-- Order ID     ContactName     Phone           OrderDate
+-- 10249	    Karin Josephs	0251-031259	    1996-07-05 00:00:00.000
+
+-- Example with 3 tables
+
+SELECT Orders.OrderID, Customers.ContactName, [Orders Details].ProductID, Orders.OrderDate
+FROM ((Orders
+INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID)
+INNER JOIN [Order Details] ON Orders.OrderID = [Order Details].OrderID);
+
+-- This query retrieves Order ID, Customer's contact name, Order Product ID and Order Date by matching CustomerID in Orders and Customer tables and matching OrderID in Orders and Order Details tables.
+
+-- Order ID     ContactName     ProductID           OrderDate
+-- 10294	    Paula Wilson	1	                1996-08-30 00:00:00.000
+
+
+-- LEFT JOIN syntax and example
+
+SELECT column_name(s)
+FROM table1
+LEFT JOIN table2
+ON table1.column_name = table2.column_name;
+
+-- Example
+
+SELECT Orders.OrderID, Customers.ContactName
+FROM Orders
+LEFT JOIN Customers
+ON Orders.CustomerID = Customers.CustomerID
+ORDER BY Customers.ContactName;
+
+-- This query retrieves all Order ID and their corresponding Customer's contact name including orders with no associated customer.
+
+-- Order ID     ContactName
+-- 10281	    Alejandra Camino
+
+
+-- RIGHT JOIN syntax and example
+
+SELECT column_name(s)
+FROM table1
+RIGHT JOIN table2
+ON table1.column_name = table2.column_name;
+
+-- Example
+
+SELECT Orders.OrderID, Customers.CompanyName
+FROM Orders
+RIGHT JOIN Customers
+ON Orders.CustomerID = Customers.CustomerID;
+
+-- This query retrieves all Company Name and their corresponding Order IDs including customers with no associated orders.
+
+-- Order ID     CompanyName
+-- 10643	    Alfreds Futterkiste
+
+
+-- FULL OUTER JOIN syntax and example
+
+SELECT column_name(s)
+FROM table1
+FULL OUTER JOIN table2
+ON table1.column_name = table2.column_name;
+
+-- Example
+
+SELECT Orders.OrderID, Customers.CompanyName, Customers.ContactName
+FROM Orders
+FULL OUTER JOIN Customers
+ON Orders.CustomerID = Customers.CustomerID
+ORDER BY Customers.ContactName;
+
+-- This query retrieves all Order IDs, Customer Company Names and Contact Names including orders with no associated customer and customers with no associated orders.
+
+-- Order ID     CompanyName         ContactName
+-- 10281	    Romero y tomillo	Alejandra Camino
+
+
+-- SELF JOIN syntax and example
+
+SELECT column_name(s)
+FROM table1 AS t1
+JOIN table1 AS t2
+ON t1.column_name = t2.column_name;
+
+-- Example (this example has done without db sample)
+
+SELECT e1.name as employee, e2.name as manager
+FROM Employees as e1
+INNER JOIN Employees as e2
+ON e1.ManagerID = e2.EmployeeID;
+
+-- This query retrieves Employee names and their corresponding manager names by joining the employees table with itself.
+
+-- employee         manager
+-- Ali Mehmet       Doruk Çoralı
+
+
+-- CROSS JOIN syntax and example
+
+SELECT column_name(s)
+FROM table1
+CROSS JOIN table2;
+
+-- Example
+
+SELECT Products.ProductID, Products.ProductName, Categories.CategoryID, Categories.CategoryName
+FROM Products
+CROSS JOIN Categories;
+
+-- This query retrieves all possible combinations of products IDs and names and categories IDs and names.
+
+-- ProductID    ProductName     CategoryID      CategoryName
+-- 1	        Chai	        1	            Beverages

Joins/HackerRank.sql

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+-- Problem: Placements -> https://www.hackerrank.com/challenges/placements/problem?isFullScreen=false
+
+-- You are given three tables: Students, Friends and Packages. Students contains two columns: ID and Name. Friends contains two columns: ID and Friend_ID (ID of the ONLY best friend). Packages contains two columns: ID and Salary (offered salary in $ thousands per month).
+-- Write a query to output the names of those students whose best friends got offered a higher salary than them. Names must be ordered by the salary amount offered to the best friends. It is guaranteed that no two students got same salary offer.
+
+-- Explanation
+
+-- Samantha's best friend got offered a higher salary than her at 11.55
+-- Julia's best friend got offered a higher salary than her at 12.12
+-- Scarlet's best friend got offered a higher salary than her at 15.2
+-- Ashley's best friend did NOT get offered a higher salary than her
+
+-- The name output, when ordered by the salary offered to their friends, will be:
+-- Samantha
+-- Julia
+-- Scarlet
+
+-- My Solution
+
+SELECT Students.Name
+FROM ((Students
+    INNER JOIN Friends ON Students.ID = Friends.ID)
+    INNER JOIN Packages as Friend_Packages ON Friend_Packages.ID = Friends.Friend_ID)
+WHERE Friend_Packages.Salary > (
+    SELECT Student_Packages.Salary
+    FROM Packages as Student_Packages
+    WHERE Student_Packages.ID = Students.ID
+)
+ORDER BY Friend_Packages.Salary;
+
+
+-- Problem: Symmetric Pairs -> https://www.hackerrank.com/challenges/symmetric-pairs/problem?isFullScreen=false
+
+-- You are given a table, Functions, containing two columns: X and Y.
+-- Two pairs (X1, Y1) and (X2, Y2) are said to be symmetric pairs if X1 = Y2 and X2 = Y1.
+-- Write a query to output all such symmetric pairs in ascending order by the value of X. List the rows such that X1 ≤ Y1.
+
+-- My Solution
+
+SELECT f1.X, f1.Y
+FROM Functions as f1
+INNER JOIN Functions as f2
+ON f1.X = f2.Y and f2.X = f1.Y
+GROUP BY f1.X, f1.Y
+HAVING COUNT(f1.X) > 1 or f1.X < f1.Y
+ORDER BY f1.X;

Joins/README.md

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+# JOINS
+
+A JOIN used to combine rows from two or more tables, based on a related column between them.
+
+
+## Different Types of Joins
+
+- **INNER JOIN:** Return records that have matching values in both tables.
+- **LEFT JOIN:** Return records of the left table and matching records in the right table.
+- **RIGHT JOIN:** Return records of the right table and matching records in the left table.
+- **FULL OUTER JOIN:** Return matching records of the left and the right table.
+- **SELF JOIN:** A self join is a unique type of join where a table is joined with itself.
+- **CROSS JOIN:** A cross join, also known as a Cartesian join, returns the Cartesian product of the two tables, meaning each row from the first table is combined with each row from the second table.
+<br />
+![img1](https://miro.medium.com/v2/resize:fit:1400/0*rFMChX4SAmQ9RzF9.png)

LICENSE

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+MIT License
+
+Copyright (c) 2022 nidea1
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -1,3 +1,41 @@
 # SQL Examples
 
-I will do functions, transactions, triggers, views and stored procedures with SQL in this repo.
+I will implement functions, transactions, triggers, views, stored procedures and other Advanced SQL Topics in this repo.
+
+Database [sample](https://github.com/microsoft/sql-server-samples/blob/master/samples/databases/northwind-pubs/instnwnd.sql) used for in this repo examples.
+
+## What is SQL?
+
+Structured Query Language (**SQL**) is programming language for storing and processing data in a relational database.
+
+## Using DB Sample
+
+```sql
+
+-- Firstly create a new database
+CREATE DATABASE ExampleDatabase
+GO
+-- After use new database for db sample
+USE ExampleDatabase
+GO
+
+-- Now copy database sample here ↓
+
+/*
+** Copyright Microsoft, Inc. 1994 - 2000
+** All Rights Reserved.
+*/
+
+-- This script does not create a database.
+-- Run this script in the database you want the objects to be created.
+-- Default schema is dbo.
+
+SET NOCOUNT ON
+GO
+
+set quoted_identifier on
+GO
+.
+.
+.
+```