PostgreSQL - JOIN day4

JOIN:

• join clause is used to combine the two or more table based on related column.

1. INNER JOIN:

• The INNER JOIN keyword selects records that have matching values in both tables.

select * from product INNER JOIN customer on product_id = cus_id;

output:

1. LEFT JOIN:

• The LEFT JOIN keyword selects ALL records from the "left" table, and the matching records from the "right" table. The result is 0 records from the right side if there is no match.

select * from product LEFT JOIN customer on product_id = cus_id;

output:

1. RIGHT JOIN:

• The RIGHT JOIN keyword selects ALL records from the "right" table, and the matching records from the "left" table. The result is 0 records from the left side if there is no match.

select product_id,product_name from product RIGHT JOIN customer on product_id = cus_id;

output:

1. OUTER JOIN:

• The FULL JOIN keyword selects ALL records from both tables, even if there is not a match. For rows with a match the values from both tables are available, if there is not a match the empty fields will get the value NULL.

select * from product FULL OUTER JOIN customer on product.price = customer.price;

output:

To Be Discussed:

1. Having

2. CROSS JOIN