Assertion. There must be some identical columns in tables in order to get cartesian product.

Reason. The cartesian product returns all possible combinations of rows from the participating tables.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Assertion. The join in which columns are compared for equality, is called an Equi-join.

Reason. The join condition can only compare columns with equal sign.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Assertion. There can be joins where all records from one of tables appear irrespective of their matching rows in the other table.

Reason. In LEFT JOIN, all rows from the left table appear in the result along with matching rows from the right table and NULL for the non-matching rows ; and same for the RIGHT JOIN where all rows came from the right table appear, along with only matching rows from the left table.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Assertion. The UNION clause combines the rows of the participating tables, removing the duplicate rows.

Reason. To retain the duplicate rows in a UNION query, UNION ALL is used.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.