Equi join and natural join: Equi join: An Equi join is a type of join that compares the columns of two tables based on a matching condition. Matching condit...
Equi join and natural join:
Equi join:
An Equi join is a type of join that compares the columns of two tables based on a matching condition. Matching conditions can be based on specific data types, such as equality (==), inequality (!=), or relationship (JOIN ON).
Example:
sql
SELECT table1.column1, table2.column2
FROM table1
JOIN table2 ON table1.id = table2.id;
In this example, the id column is used to join the table1 and table2 tables based on a matching relationship. The result set will include all the columns from both tables, where the id column values match across both tables.
Natural join:
A natural join is an equi join with an additional condition that requires a foreign key relationship between the two tables. This means that the join condition will only match rows where the corresponding columns have the same values in both tables.
Example:
sql
SELECT table1.column1, table2.column2
FROM table1
NATURAL JOIN table2 ON table1.id = table2.id
WHERE table1.column3 = table2.column4;
In this example, the id column from table1 is joined to the id column from table2 using the natural join condition. Additionally, a condition is added to ensure that only rows where column3 in table1 matches column4 in table2 are included in the result set.
Both equi joins and natural joins can be used to achieve the same results as a left outer join or an inner join, but they differ in their matching conditions and the additional join condition in the natural join