The result of a SELECT statement can contain duplicate rows. Select one: True Fa

Question

The result of a SELECT statement can contain duplicate rows. Select one: True False 2. Which of the Following Is Not A Database Model? Select one: a. Network Database Model b. Relational Database Model c. Object Oriented Database Model d. None of the above 3. The unique constraint specifies that the value of an attribute must be different from all other values of the same attribute that exist within a relation. Select one: True False 4. Select the BEST answer. In a real relational database system, if you try to join (natural join) tables R and S and R is empty (that is, it has no tuples), Select one: a. the system reports an error. b. the answer set is an empty table. c. the answer set is the same as table S. d. the answer set consists of just one row. e. an answer set is returned; however, the results are system dependent.

Explanation / Answer

Below are the answers fro the questiosn asked

Question 1

The result of a SELECT statement can contain duplicate rows. Select one: True False

Answer

True

-because the select statement can have duplicate data if you require unique data in select query then use select distinct * from table

Question 2

Which of the Following Is Not A Database Model? Select one: a. Network Database Model b. Relational Database Model c. Object Oriented Database Model d. None of the above

Answer

D:  None of the above

-all the options methioned are a database model

Question 3

The unique constraint specifies that the value of an attribute must be different from all other values of the same attribute that exist within a relation. Select one: True False

Answer

True

-Unique constraint of the column take care of the uniqueness data that stores in the column, so no repeat or duplicate entries are allowed

Question 4

Select the BEST answer. In a real relational database system, if you try to join (natural join) tables R and S and R is empty (that is, it has no tuples), Select one: a. the system reports an error. b. the answer set is an empty table. c. the answer set is the same as table S. d. the answer set consists of just one row. e. an answer set is returned; however, the results are system dependent.

Answer

b. the answer set is an empty table

- as we are doing the natural join so if the data is not present in any table or miss match data in all tables then the empty set of table data will be returned

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