Question 1

Question 1Assertion. SQL SELECT's GROUP BY clause is used to divide the result in groups.Reason. The GROUP BY clause combines all those records that have identical values in a particular field or in group by fields.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationThe GROUP BY clause combines all those records that have identical values in a particular field or a group of fields. This clause is utilised in SELECT statements to divide the result set into groups based on the values in the specified columns. Grouping can be done by a column name, or with aggregate functions in which case the aggregate produces a value for each group.

Question 2

Question 2Assertion. A GROUP BY query can also include functions.Reason. ALL SQL functions can be used in a GROUP BY query.

Accepted Answer

(c)Assertion is true but Reason is false.ExplanationA GROUP BY query can include functions. This is true because SQL allows the use of aggregate functions like COUNT(), SUM(), etc., within a GROUP BY query to perform calculations on grouped data. However, it's important to note that not all SQL functions can be used within a GROUP BY query. Only aggregate functions or functions that operate on grouped data can be used effectively in this context.

Question 3

Question 3Assertion. SQL SELECT query can also fetch rows from multiple tables.Reason. A join is a query that combines rows from two or more tables.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationSQL SELECT queries can fetch rows from multiple tables using JOIN operations. This allows retrieving data from related tables simultaneously in a single query. A join in SQL is a query that combines rows from two or more tables based on a specified condition, such as matching values in a common column.

Question 4

Question 4Assertion. Generally, a join query combines rows from multiple tables having some common column(s) and a joining condition, but not always.Reason. A Cartesian product is an unrestricted join where all possible combinations of rows from multiple tables are created without any condition on them.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationIn SQL, a join is a query that combines rows from two or more tables based on a specified condition, such as matching values in a common column. However, this matching condition is not always required; for instance, a Cartesian product is an unrestricted join where all possible combinations of rows from multiple tables are generated without any specific condition. This means that every row from one table is combined with every row from another table.

Question 5

Question 5Assertion. The join, in which columns are compared for equality, is called Equi-join.Reason. The join queries only produce combined rows from tables having some common column, when compared for equality.

Accepted Answer

(c)Assertion is true but Reason is false.ExplanationThe join, in which columns are compared for equality, is called Equi-join. Join queries in SQL can produce combined rows based on various conditions, not just equality comparisons. For example, join conditions can involve inequality comparisons (<, >, <=, >=), as well as other logical operators and functions.

Question 6

Question 6Assertion. In the result produced by a join query, there may be multiple identical columns in the final result, but not always.Reason. The join in which only one of the identical columns (coming from the joined tables) exists, is called a Natural join.

Accepted Answer

(a)Both Assertion and Reason are true and Reason is the correct explanation of Assertion.ExplanationIn the result produced by a join query, there may be multiple identical columns in the final result, but this is not always the case. Depending on the type of join and the columns involved, duplicate columns may or may not appear in the result set. A Natural join is a type of join in SQL where only one of the identical columns (coming from the joined tables) exists in the final result.

Question 7

Question 7Assertion. In order to carry out the join operation, there should be a governing condition.Reason. A join condition may be based on equality, less than, greater than or non-equality.

Accepted Answer

(d)Assertion is false but Reason is true.ExplanationIn order to carry out the join operation, there should be a governing condition is false. This is because a Cartesian join is an example of a join operation that does not require a specific condition; it combines all rows from one table with all rows from another table without any matching condition. A join condition may be based on equality, less than, greater than, or non-equality depending on the requirements of the query.

Question 8

Question 1To specify condition with a GROUP BY clause, HAVING clause is used.

Accepted Answer