sql/pl

Which command allows you to change the structure of the database?

• ALTER

• cascade

• serial

• constant

How to add an auto-incremented primary key to an existing table. We use keyword ...

• CASCADE

• SERIAL

• INCREMENT

• CONSTRAINT

Advantages of hierarchical database:I Promotes data sharing.II Database security is enforced.III It is conceptually simple due to the parent-child relationship.IV Organizational Disunity and Rigid structure.

• a. I, III, IV

• b. II, III, IV

• c. I, II, IV

• d. I, II, III

To remove all data from multiple tables, we use

• a. TRUNCATE

• b. CASCADE

• c. DROP

• d. ALTER

What is a super key?

• a. set of one or more attributes (columns), which can uniquely identify a row in a table) with no redundant attribute

• b. is a column or a group of columns in a table that reference the primary key of another table.

• c. is a set of attributes that recognizes the tuples in relation or table.

• d. set of one or more attributes (columns), which can uniquely identify a row in a table

How we call managment system for related data

• a. DBMS

• RDBMS

• HDBMS

• NDBMS

You can use aggregate functions as expressions only in the following clauses:

• LIMIT and DISTINCT clauses

• GROUP BY and JOIN clauses

• WHERE and ORDER BY clauses

• SELECT and HAVING clauses

• CREATE and DELETE clauses

What is the function of EXISTS operator in subqueries?

• returns only one row so we can use GROUP BY clause

• only cares about the number of rows returned from the subquery, not the content of the rows

• performs a calculation across a set of table rows that are somehow related to the current row

• returns from the subquery to insert into another table

• deletes all existed subqueries

Which of the following operators can be used with a subquery?

• =

• all the above

• in

• like

Which of the following statement is TRUE about FULL OUTER JOIN created on two tables Table1 and Table2?

• Retrieves both matched and unmatched rows of Table1 and Table2

• Retrieves only matched rows of table1 and Table2

• Retrieves all the unmatched rows of Table2

• Retrieves all the unmatched rows of Table1