What is the left outer join?
A left outer join is a method of combining tables. The result includes unmatched rows from only the table that is specified before the LEFT OUTER JOIN clause. If you are joining two tables and want the result set to include unmatched rows from only one table, use a LEFT OUTER JOIN clause or a RIGHT OUTER JOIN clause.
What is left join example?
The SQL LEFT JOIN returns all rows from the left table, even if there are no matches in the right table. This means that if the ON clause matches 0 (zero) records in the right table; the join will still return a row in the result, but with NULL in each column from the right table.
How do I get rid of left outer join?
You can replace a LEFT OUTER JOIN with an INNER JOIN if you add the missing values in the related table. It has not worked for you because you have added a -1 value. But the not matching value on your INNER JOIN is a 3, not a null or a -1.
What is difference between inner join and LEFT OUTER JOIN?
Sine INNER join only include matching rows, where the value of joining column is same, in the final result set, but OUTER join extends that functionality and also include unmatched rows in the final result. LEFT outer join includes unmatched rows from table written on the left of join predicate.
When to use an outer join?
An outer join is used to return results by combining rows from two or more tables. But unlike an inner join, the outer join will return every row from one specified table, even if the join condition fails.
Why do inner join vs left join?
You’ll use INNER JOIN when you want to return only records having pair on both sides , and you’ll use LEFT JOIN when you need all records from the “left” table, no matter if they have pair in the “right” table or not.
When to use a left join?
Use a left join when you want all the results from Table A, but if Table B has data relevant to some of Table A’s records, then you also want to use that data in the same query. Use a full join when you want all the results from both Tables.