Question

Which kind of a JOIN is represented by this SELECT statement:

SELECT *
FROM Products, Categories
A. inner join
B. left join
C.right join
D. cross join
E.outer join

Answer 1

The SQL SELECT statement 'SELECT * FROM Products, Categories' without any explicit join represents a cross join, which combines each row from the first table with each row of the second table.

The Correct option is; D. Cross Join.

Step-by-step explanation:

The SELECT statement SELECT * FROM Products, Categories without any explicit join condition represents a cross join in SQL. When you list tables separated by a comma in the FROM clause without specifying any type of join, what happens is that each row from the first table is combined with each row of the second table, resulting in the Cartesian product of the two tables.

This means that if the Products table has 100 rows and the Categories table has 10 rows, the cross join will result in a result set of 1,000 rows, assuming there are no additional conditions or limitations to the query.

The JOIN represented by the given SELECT statement is an INNER JOIN.

An INNER JOIN returns only the records that have matching values in both tables involved in the join. In this case, the Products and Categories tables are being joined, and the result will include only the records where the values in the common columns (if any) match.

For example:

If the Products table has a ProductID column, and the Categories table has a CategoryID column, the INNER JOIN will only include the records where the ProductID and CategoryID values match between the two tables.