SQL Joining Multiple Tables 2

Question 1

Which join returns only rows that have matching values in both tables?

Accepted Answer

INNER JOIN

Answer

INNER JOIN returns only the rows where the join condition matches in both tables.

Question 2

A LEFT JOIN between Customers and Orders returns customers with no orders. What appears in the Orders columns for those rows?

Accepted Answer

NULL

Answer

Unmatched rows from the right table produce NULL values in the result.

Question 3

Which clause is used to specify the matching condition in a join?

Accepted Answer

ON

Answer

The ON clause specifies the condition that links the joined tables.

Question 4

What does a CROSS JOIN produce?

Accepted Answer

The Cartesian product of both tables

Answer

A CROSS JOIN pairs every row of the first table with every row of the second.

Question 5

Which keyword lets you join a table to itself?

Accepted Answer

Use table aliases

Answer

A self join references the same table twice using different aliases.

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