Monday, September 19, 2011

SQL Joins

Inner joins (aka equijoins)
Basic joining (no need to specifically put in the "INNER JOIN" term). Example:
SELECT lastname, firstname, tag
FROM drivers, vehicles
WHERE drivers.location = vehicles.location

Left join
Returns all rows from the left table (table1) even if there are no matches in the right table (table2). Example:
SELECT *
FROM table1 LEFT JOIN table2 ON table1.column1 = table2.column2


Right join
Returns all rows from the right table (table2) even if there are no matches in the right table (table1). Example:
SELECT *
FROM table1 LEFT JOIN table2 ON table1.column1 = table2.column2


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