SQL PHP Cmds

sqlphp/db.notes/sql.join.queries.txt

@@ -17,6 +17,12 @@ Video: Natural join details with pictures in hindi
 https://youtu.be/zVZzJHSQlSw?t=289
 
 
+//Self join using inner, left joins
+https://dotnettutorials.net/lesson/self-join-mysql/
+
+
+//Full Join Examples
+https://mysqlcode.com/mysql-full-join/
 
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@@ -65,7 +71,7 @@ Example:
 
 
 
-3. Self Join
+3. Self Join <---
 
 //Self Join is a type of inner join, which is performed in cases where the comparison between 
 //two columns of a same table is required;
@@ -108,10 +114,163 @@ WHERE a.SALARY < b.SALARY
 ORDER BY a.SALARY;
 
 
+
+SELECT E.FullName as Employee, M.FullName as Manager
+FROM Employee E
+LEFT JOIN Employee M
+ON E.ManagerId = M.EmployeeId;
+
+
+--> Inner Self Join Example:
+
+SELECT E.FullName as Employee, M.FullName as Manager
+FROM Employee E
+INNER JOIN Employee M
+ON E.ManagerId = M.EmployeeId;
+
+
+--> Cross Self Join Example in MySQL:: 
+
+SELECT E.FullName as Employee, M.FullName as Manager
+FROM Employee E
+CROSS JOIN Employee M;
+
+
+
+
 -----x-----
 
 
 
+
+ ---> FULL JOIN <---
+
+
+The FULL JOIN or FULL OUTER JOIN keyword is used to select all records from the left table and right table.
+
+
+1.
+
+SELECT *
+FROM table1 t1
+FULL OUTER JOIN table2 t2
+ON t1.id = t2.id
+
+
+Not Work in Mysql: 
+
+
+
+2.
+
+SELECT *
+FROM table1 t1
+LEFT JOIN table2 t2
+ON t1.id = t2.id
+
+UNION ALL
+
+SELECT *
+FROM table1 t1
+RIGHT JOIN table2 t2 
+ON t1.id = t2.id
+WHERE t1.id IS NULL
+
+
+3.
+
+With two tables t1, t2:
+
+SELECT * FROM t1
+LEFT JOIN t2 ON t1.id = t2.id
+UNION
+SELECT * FROM t1
+RIGHT JOIN t2 ON t1.id = t2.id
+
+
+4. 
+
+SELECT *
+FROM Students s
+LEFT JOIN Marks m ON s.Id = m.StudentID
+UNION
+SELECT *
+FROM Students s
+RIGHT JOIN Marks m ON s.Id = m.StudentID
+WHERE s.Id IS NULL;
+
+
+
+
+5.
+Swapping Table Sides    //Changing tables positions right to left or left to right
+
+SELECT *
+FROM Marks m 
+LEFT JOIN Students s 
+ON m.StudentID = s.Id
+UNION
+SELECT *
+FROM Marks m 
+RIGHT JOIN Students s 
+ON m.StudentID = s.Id
+WHERE m.StudentID IS NULL;
+
+
+6. FULL JOIN With the WHERE clause
+
+
+SELECT *
+FROM Students s
+LEFT JOIN Marks m ON s.Id = m.StudentID
+WHERE s.Id > 5
+
+UNION
+
+SELECT *
+FROM Students s
+RIGHT JOIN Marks m ON s.Id = m.StudentID
+WHERE s.Id > 5 AND s.Id IS NULL;
+
+
+7. 
+
+SELECT *
+FROM Students s
+LEFT JOIN Marks m
+ON s.Id = m.StudentID
+WHERE m.StudentID > 5
+
+UNION ALL
+
+SELECT *
+FROM Students s
+RIGHT JOIN Marks m
+ON s.Id = m.StudentID
+WHERE s.Id IS NULL AND m.StudentID > 5;
+
+
+8. 
+FULL JOIN in MariaDB: 
+
+SELECT * FROM Students s LEFT OUTER JOIN Marks m ON s.ID=m.StudentID 
+UNION 
+SELECT * FROM Students s RIGHT OUTER JOIN Marks m ON s.ID=m.StudentID;
+
+
+
+
+---x----
+
+
+
+
+
+
+
+
+
+
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