Concurrency control is used .

A database system without concurrency control may cause:

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

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

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 .

Which of the following statements about normal forms is/are true?

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

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

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

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