DEVOIR 2013-2014, SQL, CORRECTION 
  
Question 1

SELECT nom, regid FROM regions WHERE nom LIKE "Br%"

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Question 2

SELECT nom, regid FROM departements WHERE 
       regid = (SELECT regid FROM regions WHERE nom LIKE "Br%")

SELECT nom, regid FROM departements AS d WHERE 
       d.regid =  (SELECT r.regid FROM regions AS r WHERE nom LIKE "Br%")

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Question 3

SELECT d.ChefLieu, c.nom FROM departements AS d JOIN communes AS c 
       ON d.ChefLieu = c.ComId
       WHERE d.DepId IN
       (SELECT d.DepId FROM departements 
       	       WHERE d.regid =  
	       (SELECT r.regid FROM regions AS r WHERE nom LIKE "Br%"))
ORDER BY c.nom

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Création d'une vue :

CREATE VIEW combretagne AS
       SELECT c.ComId, c.nom, d.DepId, d.nom FROM
       	      communes AS c JOIN departements AS d
	      ON c.DepId = d.DepId
	      	 WHERE d.RegId = 
		 (SELECT r.RegId FROM regions AS r WHERE r.nom LIKE "Br%")

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Question 4

SELECT COUNT(*) FROM combretagne 
       WHERE Commune LIKE "Plou%"

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Question 5

SELECT COUNT(*) FROM combretagne 
       WHERE Commune LIKE "Plou%" OR Commune LIKE "Ker%"

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Création d'une vue 

CREATE VIEW popbretagne AS
       SELECT b.ComId, b.Commune, b.DepId, b.Departement, 
       p.P09_POP AS Pop, p.SUPERF AS superficie FROM
       		 combretagne AS b JOIN population AS p
       		 ON b.ComId = p.CodGeo

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Question 6

SELECT DepId, Commune, Pop FROM popbretagne
       WHERE Commune LIKE "%z"
       ORDER BY Pop

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Question 7

SELECT DepId, Commune, Pop/superficie AS densite FROM popbretagne
       WHERE Commune LIKE "%z"
       ORDER BY densite DESC

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Question 8

SELECT AVG(Pop) FROM popbretagne

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Question 9

SELECT  depid, AVG(Pop) AS "population moyenne du département" 
	FROM popbretagne 
	GROUP BY depid

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Question 10

SELECT COUNT(*) FROM popbretagne 
       WHERE Pop < (SELECT AVG(Pop) FROM popbretagne)








