Question

You can perform ANSI joins using the keywords NATURAL JOIN, or USING clause, or the ON clause. Describe all three.

Answer 1

An ANSI join is a type of join operation in a relational database that follows the ANSI SQL standard. There are three ways to perform ANSI joins: NATURAL JOIN, USING clause, and ON clause.

Step-by-step explanation:

An ANSI join is a type of join operation in a relational database that follows the ANSI SQL standard. There are three ways to perform ANSI joins:

1. NATURAL JOIN: This type of join automatically matches columns in the two tables with the same name, without requiring any additional specifications.
2. USING clause: This type of join specifies the columns to be matched between the tables, using the USING keyword followed by a comma-separated list of column names.
3. ON clause: This type of join specifies the join conditions using the ON keyword followed by a Boolean expression that determines how the tables are linked.

For example, let's say we have two tables: 'customers' and 'orders'. Here's how each type of ANSI join would look like:

• NATURAL JOIN: SELECT * FROM customers NATURAL JOIN orders;
• USING clause: SELECT * FROM customers JOIN orders USING (customer_id);
• ON clause: SELECT * FROM customers JOIN orders ON customers.customer_id = orders.customer_id;