Adding left join example.

class2016/c4_5/Iliyan_Germanov_B_17/selects.sql

@@ -1,15 +1,36 @@
 USE calendar;
 
 SELECT Users.name FROM Users 
-INNER JOIN Groups_Users ON Users.id = Groups_Users.user_id;
+INNER JOIN Groups_Users ON Users.id = Groups_Users.user_id
+INNER JOIN Groups ON Groups_Users.group_id = Groups.id;
 
 SELECT Users.name FROM Users 
 INNER JOIN Groups_Users ON Users.id = Groups_Users.user_id
-INNER JOIN Groups_Events ON Groups_Users.group_id = Groups_Events.group_id;
+INNER JOIN Groups_Events ON Groups_Users.group_id = Groups_Events.group_id
+INNER JOIN Events ON Groups_Events.event_id = Events.id;
 
 SELECT Users.name, Events.name FROM Users 
 INNER JOIN Groups_Users ON Users.id = Groups_Users.user_id
 INNER JOIN Groups_Events ON Groups_Users.group_id = Groups_Events.group_id
 INNER JOIN Event ON Groups_Events.event_id = Events.id
 WHERE Events.name = "AMG";
 
+#LEFT JOIN EXAMPLE
+SELECT Users.name, Groups.name FROM Users
+LEFT JOIN Groups_Users ON User.id = Groups_Users.user_id
+LEFT JOIN Groups ON Groups.id = Groups_Users.group_id;
+
+#OUTTER JOIN EXAMPLE
+SELECT Users.name, Groups.name FROM Users
+LEFT JOIN Groups_Users ON User.id = Groups_Users.user_id
+LEFT JOIN Groups ON Groups.id = Groups_Users.group_id
+UNION
+SELECT Users.name, Groups.name FROM Users
+RIGHT JOIN Groups_Users ON User.id = Groups_Users.user_id
+RIGHT JOIN Groups ON Groups.id = Groups_Users.group_id;
+
+#All users without groups
+SELECT User.name FROM Users
+LEFT JOIN Groups_Users ON User.id = Groups_Users.user_id
+WHERE Groups_Users.user_id IS NULL;
+

class2016/c4_5/Stefan_Iliev_B_28/selects.sql

@@ -1,15 +1,36 @@
 USE calendar;
 
 SELECT Users.name FROM Users 
-INNER JOIN Groups_Users ON Users.id = Groups_Users.user_id;
+INNER JOIN Groups_Users ON Users.id = Groups_Users.user_id
+INNER JOIN Groups ON Groups_Users.group_id = Groups.id;
 
 SELECT Users.name FROM Users 
 INNER JOIN Groups_Users ON Users.id = Groups_Users.user_id
-INNER JOIN Groups_Events ON Groups_Users.group_id = Groups_Events.group_id;
+INNER JOIN Groups_Events ON Groups_Users.group_id = Groups_Events.group_id
+INNER JOIN Events ON Groups_Events.event_id = Events.id;
 
 SELECT Users.name, Events.name FROM Users 
 INNER JOIN Groups_Users ON Users.id = Groups_Users.user_id
 INNER JOIN Groups_Events ON Groups_Users.group_id = Groups_Events.group_id
 INNER JOIN Event ON Groups_Events.event_id = Events.id
 WHERE Events.name = "AMG";
 
+#LEFT JOIN EXAMPLE
+SELECT Users.name, Groups.name FROM Users
+LEFT JOIN Groups_Users ON User.id = Groups_Users.user_id
+LEFT JOIN Groups ON Groups.id = Groups_Users.group_id;
+
+#OUTTER JOIN EXAMPLE
+SELECT Users.name, Groups.name FROM Users
+LEFT JOIN Groups_Users ON User.id = Groups_Users.user_id
+LEFT JOIN Groups ON Groups.id = Groups_Users.group_id
+UNION
+SELECT Users.name, Groups.name FROM Users
+RIGHT JOIN Groups_Users ON User.id = Groups_Users.user_id
+RIGHT JOIN Groups ON Groups.id = Groups_Users.group_id;
+
+#All users without groups
+SELECT User.name FROM Users
+LEFT JOIN Groups_Users ON User.id = Groups_Users.user_id
+WHERE Groups_Users.user_id IS NULL;
+