Option (A) returns eid’s which owns every brand of the relation Brand.
In relational algebra, divide (/) is not a basic operator and it can be derived from the basic operators. In option (B), the divide operator is derived using basic operators and which is equivalent to option (A)

Explanation :

Probability of 1st condition being satisfied(say P(A)) = 10/15 = 2/3

Probability of 2nd condition being satisfied(say P(B)) = 1/20

Probability of both conditions being satisfied(say P(A intersection B)) = 2/3*1/20 = 1/30

Probability of any one condition being satisfied = P(A union B) = P(A)+P(B)-P(A intersection B) = 2/3 + 1/20 - 1/30 = 41/60

therefore, expected number of tuples = (41/60)*1200 = 820

→ Candidate means uniquely identified key.
→ In the above table, Room having duplicate values. So, we can’t say room is candidate key
→ The last name also having duplicates. So, we can’t say the last name is candidate key.
→ Shift also having duplicate keys, so we can’t say shift also a candidate key.
→ Combining Room and Shift we can say that candidate key.

DCL(Data Control Language) includes commands such as GRANT and REVOKE which mainly deals with the rights, permissions and other controls of the database system.
Examples of DCL commands:
GRANT-gives user’s access privileges to database.
REVOKE-withdraw user’s access privileges given by using the GRANT command.

→ A data dictionary(or) metadata repository, as defined in the IBM Dictionary of Computing, is a "centralized repository of information about data such as meaning, relationships to other data, origin, usage, and format".
→ Oracle defines it as a collection of tables with metadata. The term can have one of several closely related meanings pertaining to databases and database management systems (DBMS)
1. A document describing a database or collection of databases
2. An integral component of a DBMS that is required to determine its structure
3. A piece of middleware that extends or supplants the native data dictionary of a DBMS

1. To understand how pointers and their associated data elements are allocated in Microsoft RPC, you have to differentiate between top-level pointers and embedded pointers

2. Top-level pointers are those that are specified as the names of parameters in function prototypes. Top-level pointers and their referents are always allocated on the server.

3. Embedded pointers are pointers that are embedded in data structures such as arrays, structures, and unions. When embedded pointers only write output to a buffer and are null on input, the server application can change their values to non-null. In this case, the client stubs allocate new memory for this data.

4. If the embedded pointer is not null on the client before the call, the stubs do not allocate memory on the client on return. Instead, the stubs attempt to write the memory associated with the embedded pointer into the existing memory on the client associated with that pointer, overwriting the data already there.

Inner Join :
Inner join combines two tables having a common attributes.
While combining it only join the rows of two tables having same value in common attribute.
So, in that way inner join return the records having matching values in both the tables.