What Does Full Join Do In SQL?

How do you do a full join in SQL?

The SQL FULL JOIN syntaxSELECT column-names.FROM table-name1 FULL JOIN table-name2.ON column-name1 = column-name2.WHERE condition..

How does full outer join work?

In SQL the FULL OUTER JOIN combines the results of both left and right outer joins and returns all (matched or unmatched) rows from the tables on both sides of the join clause. Let’s combine the same two tables using a full join. Here is an example of full outer join in SQL between two tables.

What is difference between inner join and equi join?

An equijoin is a join with a join condition containing an equality operator. An equijoin returns only the rows that have equivalent values for the specified columns. An inner join is a join of two or more tables that returns only those rows (compared using a comparison operator) that satisfy the join condition.

What does a full join do?

The FULL OUTER JOIN keyword returns all records when there is a match in left (table1) or right (table2) table records. Note: FULL OUTER JOIN can potentially return very large result-sets! Tip: FULL OUTER JOIN and FULL JOIN are the same.

Does not exist in SQL?

The SQL NOT EXISTS Operator will act quite opposite to EXISTS Operator. It is used to restrict the number of rows returned by the SELECT Statement. The NOT EXISTS in SQL Server will check the Subquery for rows existence, and if there are no rows then it will return TRUE, otherwise FALSE.

Why use 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. Take the phone directory example above.

Why is self Join needed?

It is useful for querying hierarchical data or comparing rows within the same table. A self join uses the inner join or left join clause. Because the query that uses self join references the same table, the table alias is used to assign different names to the same table within the query.

What is difference between Equi join and Non Equi join?

Summary. A join that is using only the “equals” comparison in the join condition is called Equi-Join. A Join that has at least one comparison in the join condition that is not an “equals” comparison is called a Nonequi-Join. Nonequi Joins are often used for calculations of running totals and similar metrics.

Why use full join in SQL?

SQL full outer join is used to combine the result of both left and right outer join and returns all rows (don’t care its matched or unmatched) from the both participating tables. Syntax for full outer join: … FULL OUTER JOIN table2. ON table1.

What is the difference between full join and full outer join?

An Outer join basically differs from the Inner join in how it handles the false match condition. … Right Outer Join: Returns all the rows from the RIGHT table and matching records between both the tables. Full Outer Join: It combines the result of the Left Outer Join and Right Outer Join.

What is equi join?

An equi join is a type of join that combines tables based on matching values in specified columns. … The column names do not need to be the same. The resultant table contains repeated columns. It is possible to perform an equi join on more than two tables.