left outer join code example

Example 1: mysql left join

/*Two tables: CUSTOMERS table and ORDERS table.
ORDERS table contains STATUS attribute.*/
SELECT 
    customers.customerNumber, 
    customerName, 
    orderNumber, 
    status
FROM
    customers
LEFT JOIN orders ON 
    orders.customerNumber = customers.customerNumber;

Example 2: sql left join

SELECT table1.column1, table2.column2...
FROM table1
LEFT JOIN table2
ON table1.common_field = table2.common_field;

Example 3: right join

RIGHT JOIN: Matching part from both
table and unmatching part from right table.

Example 4: left join

Matching part from both table and unmatching part from left table.

Example 5: Perform a left outer join of self and other.

x = sc.parallelize([("a", 1), ("b", 4)])
y = sc.parallelize([("a", 2)])
sorted(x.leftOuterJoin(y).collect())
# [('a', (1, 2)), ('b', (4, None))]

Example 6: right outer vs left outer join

LEFT OUTER JOIN:
is used when retrieving data from
multiple tables and will return
left table and any matching right table records.

RIGHT OUTER JOIN:
is used when retrieving data from
multiple tables and will return right
table and any matching left table records