SELECT from two tables

SELECT * FROM Table1;
SELECT * FROM Table2;

INNER JOIN

SELECT *
 FROM Table1 t1
INNER JOIN Table2 t2
   ON t1.fk = t2.id;

LEFT OUTER JOIN

SELECT *
 FROM Table1 t1
LEFT OUTER JOIN Table2 t2
 ON t1.fk = t2.id;

RIGHT OUTER JOIN

SELECT *
 FROM Table1 t1
RIGHT OUTER JOIN Table2 t2
 ON t1.fk = t2.id;

SEMI JOIN – Similar to INNER JOIN, with less duplication.

SELECT *
FROM Table1 t1
WHERE EXISTS (SELECT 1
               FROM Table2 t2
               WHERE t1.fk = t2.id
            );

ANTI SEMI JOIN

SELECT *
FROM Table1 t1
WHERE NOT EXISTS (SELECT 1  
                   FROM Table2 t2
                   WHERE t1.fk = t2.id
                );

LEFT OUTER JOIN with exclusion

SELECT *
 FROM Table1 t1
LEFT OUTER JOIN Table2 t2
  ON t1.fk = t2.id
WHERE t2.id is null;

RIGHT OUTER JOIN with exclusion

SELECT *
 FROM Table1 t1
RIGHT OUTER JOIN Table2 t2
  ON t1.fk = t2.id
WHERE t1.fk is null;

FULL OUTER JOIN

SELECT * FROM Table1 t1
 LEFT OUTER JOIN Table2 t2
  ON t1.fk = t2.id
UNION
SELECT * FROM Table1 t1
 RIGHT OUTER JOIN Table2 t2
  ON t1.fk = t2.id;

FULL OUTER JOIN with exclusion

SELECT * FROM Table1 t1
 LEFT OUTER JOIN Table2 t2
  ON t1.fk = t2.id
 WHERE t2.id IS NOT NULL
UNION
SELECT * FROM Table1 t1
 RIGHT OUTER JOIN Table2 t2
  ON t1.fk = t2.id
 WHERE t1.ID IS NOT NULL;

Two INNER JOINs

SELECT *
 FROM Table1 t1
INNER JOIN Table2 t2
  ON t1.fk = t2.id
INNER JOIN Table3 t3
  ON t1.fk_table3 = t3.id;

Two LEFT OUTER JOINS

SELECT *
 FROM Table1 t1
LEFT OUTER JOIN Table2 t2
  ON t1.fk = t2.id
LEFT OUTER JOIN Table3 t3
  ON t1.fk_table3 = t3.id;

INNER JOIN and a LEFT OUTER JOIN

SELECT *
 FROM Table1 t1
INNER JOIN Table2 t2
  ON t1.fk = t2.id
LEFT OUTER JOIN Table3 t3
  ON t1.fk_table3 = t3.id;