SQL OUTER JOIN – left outer join. SQL left outer join is also known as SQL left join. Suppose, we want to join two tables: A and B. An outer join request must appear after the FROM keyword and before the WHERE clause (if one exists). For example, the following SQL statements create the same result set that lists all customers and shows which has open orders.
This lesson of the SQL tutorial for data analysis introduces the concept of outer joins. Unlike inner joins , outer joins can return unmatched rows in one or both tables. LEFT OUTER JOIN in SQL. It preserves the unmatched rows from the first (left) table, joining them with a NULL row in the shape of the second (right) table. The joined table retains each row—even if no other matching row exists.
In SQL , a join is used to compare and combine — literally join — and return specific rows of data from two or more tables in a database. An inner join finds and returns matching data from tables, while an outer join finds and returns matching. FROM cities, countries WHERE cities. RIGHT OUTER JOIN - fetches data if present in the right table.
The full outer join or full join returns all rows from both tables, matching up the rows wherever a match can be made and placing NULLs in the places where no matching row exists. FULL OUTER JOIN - fetches data if present in either of the two tables.
