What is inner and LEFT OUTER JOIN? Is there way to do multiple left outer joins in Oracle? The following Venn diagram illustrates how the LEFT JOIN clause works. The LEFT JOIN is also referred as LEFT OUTER JOIN.
The intersection is the rows in the A table. Left outer join is also known as Left join , it will retrieves all rows from left table and matching rows from right table also retrieves all matching records from both the tables, if we want to fetch all record from the first table and doesn’t need any record from the second table then we create left join second table such as that column has. In this syntax, the OUTER keyword is optional. The full outer join combines the of both left join and right join. If the rows in the joined table do not match, the full outer join sets NULL values for every column of the table that does not have the matching row.
This CROSS JOIN produces exactly the rows we need without any surplus. Avoids the need for a later GROUP BY. LEFT JOIN tto that, using grp in addition to tbl1_fk to make it distinct.
Sort any way you like - which is possible now with a. It then looks to see if there are any rows from tthat are not in the result set. If so, it adds in those rows placing NULLs for all the fields of t2. This type of join returns all rows from the LEFT -hand table specified in the ON condition and only those rows from the other table where the joined fields are equal ( join condition is met).