Answers for "sql left join"

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;

sql right join

SELECT *
FROM table_1
RIGHT JOIN table_2
ON table_1.common_field = table_2.common_field;

sql left join

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

ms sql left join select

SELECT * FROM 
(SELECT [column] FROM [table]) a
LEFT JOIN (SELECT [column1], [columnn2] FROM [table]) b
ON a.column = b.column1

ms sql left join select

SELECT * FROM 
(SELECT [UserID] FROM [User]) a
LEFT JOIN (SELECT [TailUser], [Weight] FROM [Edge] WHERE [HeadUser] = 5043) b
ON a.UserId = b.TailUser

sql left join

-- LEFT OUTER JOIN is equivalent to LEFT JOIN
-- b.VALUE1 is null when ID not in table2 (idem for c.VALUE1 in table3)
SELECT a.ID, a.NAME, b.VALUE1, c.VALUE1 FROM table1 a 
  LEFT OUTER JOIN table2 b ON a.ID = b.ID
  LEFT OUTER JOIN table3 c ON a.ID = c.ID
WHERE a.ID >= 1000;

-- ⇓ Test it ⇓ (Fiddle source link)