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TABLE CREATION
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CREATE TABLE tabnatural1(a INT, b INT, c VARCHAR(10));
CREATE TABLE tabnatural2(a INT, b INT, d VARCHAR(10));

INSERT INTO tabnatural1 VALUES(1, 11, 'x');
INSERT INTO tabnatural1 VALUES(2, 22, 'y');
--------------
| a | b  | c |
--------------
| 1 | 11 | x |
| 2 | 22 | y |
--------------

INSERT INTO tabnatural2 VALUES(2, 22, 'y');
INSERT INTO tabnatural2 VALUES(3, 33, 'z');
--------------
| a | b  | d |
--------------
| 2 | 22 | y |
| 3 | 33 | z |
--------------
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, / CROSS JOIN / INNER JOIN / JOIN 
All are equivalent without USING / ON
****************************************************************
SELECT * FROM tabnatural1 CROSS JOIN tabnatural2;
or 
SELECT * FROM tabnatural1 INNER JOIN tabnatural2; 
or 
SELECT * FROM tabnatural1 JOIN tabnatural2; 
or 
SELECT * FROM tabnatural1, tabnatural2; 
---------------------------
| a | b  | c | a | b  | d |
---------------------------
| 2 | 22 | y | 2 | 22 | y |
| 1 | 11 | x | 2 | 22 | y |
| 2 | 22 | y | 3 | 33 | z |
| 1 | 11 | x | 3 | 33 | z |
---------------------------

SELECT * FROM tabnatural2 CROSS JOIN tabnatural1;
or 
SELECT * FROM tabnatural2 INNER JOIN tabnatural1;
or 
SELECT * FROM tabnatural2 JOIN tabnatural1; 
or 
SELECT * FROM tabnatural2, tabnatural1;
---------------------------
| a | b  | d | a | b  | c |
---------------------------
| 3 | 33 | z | 1 | 11 |	x |
| 2 | 22 | y | 1 | 11 |	x |
| 3 | 33 | z | 2 | 22 | y |
| 2 | 22 | y | 2 | 22 |	y |
---------------------------
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****************************************************************




****************************************************************
NATURAL JOIN / NATURAL INNER JOIN
Cannot use USING / ON with NATURAL JOIN / NATURAL INNER JOIN
Can use WHERE with NATURAL JOIN / NATURAL INNER JOIN
****************************************************************
SELECT * FROM tabnatural1 NATURAL JOIN tabnatural2;
or 
SELECT * FROM tabnatural1 NATURAL INNER JOIN tabnatural2; 
------------------
| a | b  | c | d |
------------------
| 2 | 22 | y | y |
------------------

SELECT * FROM tabnatural2 NATURAL JOIN tabnatural1;
or 
SELECT * FROM tabnatural2 NATURAL INNER JOIN tabnatural1; 
------------------
| a | b  | d | c |
------------------
| 2 | 22 | y | y |
------------------
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****************************************************************
****************************************************************
SELECT * FROM tabnatural1 NATURAL JOIN tabnatural2;
is equivalent to
SELECT * FROM tabnatural1 CROSS JOIN tabnatural2 USING (a,b);
is equivalent to
SELECT * FROM tabnatural1 INNER JOIN tabnatural2 USING (a,b);
is equivalent to
SELECT * FROM tabnatural1 JOIN tabnatural2 USING (a,b);
if tabnatural1 and tabnatural2 have two common atributes named a and b
------------------
| a | b  | c | d |
------------------
| 2 | 22 | y | y |
------------------
With , we cannot use USING / ON
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****************************************************************
****************************************************************
SELECT * FROM tabnatural1 CROSS JOIN tabnatural2 ON tabnatural1.a = tabnatural2.a AND tabnatural1.b = tabnatural2.b;
is equivalent to
SELECT * FROM tabnatural1 INNER JOIN tabnatural2 ON tabnatural1.a = tabnatural2.a AND tabnatural1.b = tabnatural2.b;
is equivalent to
SELECT * FROM tabnatural1 JOIN tabnatural2 ON tabnatural1.a = tabnatural2.a AND tabnatural1.b = tabnatural2.b;
---------------------------
| a | b  | c | a | b  | d |
---------------------------
| 2 | 22 | y | 2 | 22 | y |
---------------------------

SELECT * FROM tabnatural2 CROSS JOIN tabnatural1 ON tabnatural2.a = tabnatural1.a AND tabnatural2.b = tabnatural1.b;
is equivalent to
SELECT * FROM tabnatural2 INNER JOIN tabnatural1 ON tabnatural2.a = tabnatural1.a AND tabnatural2.b = tabnatural1.b;
is equivalent to
SELECT * FROM tabnatural2 JOIN tabnatural1 ON tabnatural2.a = tabnatural1.a AND tabnatural2.b  = tabnatural1.b;
---------------------------
| a | b  | d | a | b  | c |
---------------------------
| 2 | 22 | y | 2 | 22 | y |
---------------------------
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****************************************************************
****************************************************************
SELECT * FROM tabnatural1 NATURAL LEFT OUTER JOIN tabnatural2;
or 
SELECT * FROM tabnatural1 LEFT OUTER JOIN tabnatural2 USING(a,b);
if tabnatural1 and tabnatural2 have two common atributes named a and b
---------------------
| a | b  | c | d    |
---------------------
| 1 | 11 | x | NULL |
| 2 | 22 | y | y    |
---------------------

SELECT * FROM tabnatural2 NATURAL LEFT OUTER JOIN tabnatural1;
or 
SELECT * FROM tabnatural2 LEFT OUTER JOIN tabnatural1 USING(a,b);
if tabnatural1 and tabnatural2 have two common atributes named a and b
---------------------
| a | b  | d | c    |
---------------------
| 2 | 22 | y | y    |
| 3 | 33 | z | NULL |
---------------------

SELECT * FROM tabnatural1 NATURAL RIGHT OUTER JOIN tabnatural2;
or 
SELECT * FROM tabnatural1 RIGHT OUTER JOIN tabnatural2 USING(a,b);
if tabnatural1 and tabnatural2 have two common atributes named a and b
---------------------
| a | b  | d | c    |
---------------------
| 2 | 22 | y | y    |
| 3 | 33 | z | NULL |
---------------------

SELECT * FROM tabnatural2 NATURAL RIGHT OUTER JOIN tabnatural1;
or 
SELECT * FROM tabnatural2 RIGHT OUTER JOIN tabnatural1 USING(a,b);
if tabnatural1 and tabnatural2 have two common atributes named a and b
---------------------
| a | b  | c | d    |
---------------------
| 1 | 11 | x | NULL |
| 2 | 22 | y | y    |
---------------------
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****************************************************************
LEFT OUTER JOIN / LEFT JOIN
RIGHT OUTER JOIN / RIGHT JOIN
****************************************************************
SELECT * FROM tabnatural1 LEFT OUTER JOIN tabnatural2 ON tabnatural1.a = tabnatural2.a AND tabnatural1.b = tabnatural2.b;
-----------------------------------
| a | b  | c | a    | b    | d    |
-----------------------------------
| 1 | 11 | x | NULL | NULL | NULL |
| 2 | 22 | y | 2    | 22   | y    |
-----------------------------------

SELECT * FROM tabnatural2 LEFT OUTER JOIN tabnatural1 ON tabnatural2.a = tabnatural1.a AND tabnatural2.b = tabnatural1.b;
-----------------------------------
| a | b  | d | a    | b    | c    |
-----------------------------------
| 2 | 22 | y | 2    | 22   | y    |
| 3 | 33 | z | NULL | NULL | NULL |
-----------------------------------

SELECT * FROM tabnatural1 RIGHT OUTER JOIN tabnatural2 ON tabnatural1.a = tabnatural2.a AND tabnatural1.b = tabnatural2.b;
-----------------------------------
| a    | b     | c   | a | b | d  |
-----------------------------------
| 2    | 22   | y    | 2 | 22 | y |
| NULL | NULL | NULL | 3 | 33 | z |
-----------------------------------

SELECT * FROM tabnatural2 RIGHT OUTER JOIN tabnatural1 ON tabnatural2.a = tabnatural1.a AND tabnatural2.b = tabnatural1.b;
-----------------------------------
| a   | b    | d    | a | b  | c |
-----------------------------------
|NULL | NULL | NULL | 1 | 11 | x |
| 2   | 22   | y    | 2 | 22 | y |
-----------------------------------
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****************************************************************
FULL OUTER JOIN (Not in Mysql)
****************************************************************
(SELECT a,b,c,d FROM tabnatural1 NATURAL LEFT OUTER JOIN tabnatural2)
UNION
(SELECT a,b,c,d FROM tabnatural1 NATURAL RIGHT OUTER JOIN tabnatural2);
------------------------
| a | b  | c    | d    |
------------------------
| 1 | 11 | x    | NULL |
| 2 | 22 | y    | y    |
| 3 | 33 | NULL | w    |
------------------------
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****************************************************************




SELECT * FROM tabnatural1 JOIN tabnatural2 ON tabnatural1.a = tabnatural2.a AND tabnatural1.b = tabnatural2.b
is equivalent to
SELECT * FROM tabnatural1, tabnatural2 WHERE tabnatural1.a = tabnatural2.a AND tabnatural1.b = tabnatural2.b
-----------------------------------
| a    | b     | c   | a | b | d  |
-----------------------------------
| 2    | 22   | y    | 2 | 22 | y |
-----------------------------------