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full outer join in sql
Full Join in SQL is a type of join operation that combines the results of two or more tables. It returns all rows when there is at least one match in either left or right table. It is also known as Full Outer Join. It is used to combine the results of two or more tables, even if there are no matches in the other table.
Akash is a data analyst working for a large retail company. He was tasked with creating a report that included data from two different tables. The tables contained information about customers and their orders, as well as orders and their respective items. Akash knew that to get the complete picture of the data. He would need to use a full join in SQL. So, he wrote a query, but unfortunately, it was wrong. Let's help him with it.
Full Join in SQL is a type of join operation that returns all rows from the left table and all rows from the right table. It combines the results of two or more tables, even if no matches exist in the other table.
The syntax for a full join in SQL is:
SELECT * FROM table_1 FULL JOIN table_2 ON table_1.column_name=table_2.column_name;
Let's consider two tables, Table A and Table B. Table A contains information about customers and their orders. Table B contains information about orders and their respective items.
We can use a full join in SQL to join these two tables together. Here is an example of a full join in SQL:
SELECT * FROM table_A FULL JOIN table_B ON table_A.order_id = table_B.order_id;
This query will return all rows from both tables, regardless of whether there's a matching arrange within the other table. This implies that even in case an order in Table A does not have any things in Table B, the row from Table A will still be included within the result set.
The best thing about employing a full join in SQL is that it permits you to combine the results of two or more tables, even if there are no matches within the other table. This can be valuable after you are trying to get a total picture of the information.
The main confinement of employing a full join in SQL is that it can be moderate and resource intensive, particularly when the tables being joined are huge. Furthermore, since it returns all rows from both tables, it can be troublesome to interpret the results.
Alternatives for Full Join
A union operation is the main alternative to a full join in SQL. A union operation combines the comes about of two or more tables, but it, as it were, returns distinct rows. This implies that in case an order has numerous things related with it, the query will, as it were, return the order once.
Common Mistakes of Full Join
One of the most common mistakes when using a full join in SQL is to forget to include the ON clause. The ON clause specifies the column or columns that should be used to join the two tables. Without the ON clause, the query will return all rows from both tables regardless of whether there is a match.
Key Takeaways for Full Join in SQL
Akash successfully completed the task he was given. He utilized a full join in SQL to combine the information from two diverse tables, and he was able to urge the point-by-point report he required. His supervisors lauded his work, and they were exceptionally satisfied with the comes about.
Answer: D. Outer Join
Answer: C. All rows from both tables
Answer: C. Forgetting to include the ON clause
Answer: D. Union