State whether the following statement is true or false:

A database table must have only one primary key and one super key.

Which attributes is represented by the entity-relationship (E-R) diagram given in the image?

Suppose there are two relations: R1 and R2. If C1 and C2 are the selection conditions, and A1 and A2 are the attributes of the relation R1, then which of the given query transformations are correct? 1. 0C1 (0C1 (R1)) -> 0C2 (0C2 (R1)) 2. 0C1 (nA1 (R1)) -> nAl (0C1 (R1)) 3. 0C1 (R1 U R2) -> 0C1 (R1) U 0C1 (R2)

Which database security mechanisms is used to enforce multilevel security by classifying users and data into various security levels? 1. Mandatory security mechanisms 2. Discretionary security mechanisms

Which of the given options is targeted and focused on a single subset of an organization?

Consider a table named 'Account,' having the following fields.

Consider the schema R = (ABCD) and the functional dependencies A -> B, B -> C, C -> D and D -> A. Let R = (R1 and R2) be a decomposition, such that R1 {'1 R2 = cp. The decomposition is in .

Restriction of_ from the basic relational model has been removed in the nested relational model.

The hash address space in static hashing is not always the same.

A database system without concurrency control may cause:

Concurrency control is used .