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I have created 2 tables as
CREATE TABLE table1(customerName VARCHAR(20),custid NUMBER ,order_id NUMBER ,price NUMBER );
CREATE TABLE table2(id NUMBER ,salary NUMBER );
Now, I tried to use the queries
SELECT t1.customername,t1.custid,t2.salary FROM table1 t1 left join table2 t2 ON t1.custid = t2.id;
SELECT t1.customername,t1.custid,t2.salary FROM table1 t1 left outer join table2 t2 ON t1.custid = t2.id;
But I get the same output. Is there any difference between them internally in their working ? or are both same!?
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There really is no difference between a LEFT JOIN and a LEFT OUTER JOIN. Both versions of the syntax will produce the exact same result in PL/SQL. Some people do recommend including outer in a LEFT JOIN clause so it's clear that you're creating an outer join, but that's entirely optional.
Avoiding Duplicates Again, if we perform a left outer join where date = date, each row from Table 5 will join on to every matching row from Table 4. However, in this case, the join will result in 4 rows of duplicate dates in the joined DataSet (see Table 6).
Left Outer Join: Returns all the rows from the LEFT table and matching records between both the tables. Right Outer Join: Returns all the rows from the RIGHT table and matching records between both the tables.
The OUTER keyword is optional across most popular SQL distributions, which means there is absolutely no difference between a LEFT JOIN and a LEFT OUTER JOIN
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