Database Multiple Choice Questions on “OLAP”.
1. OLAP stands for
a) Online analytical processing
b) Online analysis processing
c) Online transaction processing
d) Online aggregate processing
Answer: a
Clarification: OLAP is the manipulation of information to support decision making.
2. Data that can be modeled as dimension attributes and measure attributes are called _______ data.
a) Multidimensional
b) Singledimensional
c) Measured
d) Dimensional
Answer: a
Clarification: Given a relation used for data analysis, we can identify some of its attributes as measure attributes, since they measure some value, and can be aggregated upon.Dimension attribute define the dimensions on which measure attributes, and summaries of measure attributes, are viewed.
3. The generalization of cross-tab which is represented visually is ____________ which is also called as data cube.
a) Two dimensional cube
b) Multidimensional cube
c) N-dimensional cube
d) Cuboid
Answer: a
Clarification: Each cell in the cube is identified for the values for the three dimensional attributes.
4. The process of viewing the cross-tab (Single dimensional) with a fixed value of one attribute is
a) Slicing
b) Dicing
c) Pivoting
d) Both Slicing and Dicing
Answer: a
Clarification: The slice operation selects one particular dimension from a given cube and provides a new sub-cube. Dice selects two or more dimensions from a given cube and provides a new sub-cube.
5. The operation of moving from finer-granularity data to a coarser granularity (by means of aggregation) is called a ________
a) Rollup
b) Drill down
c) Dicing
d) Pivoting
Answer: a
Clarification: The opposite operation—that of moving fromcoarser-granularity data to finer-granularity data—is called a drill down.
6. In SQL the cross-tabs are created using
a) Slice
b) Dice
c) Pivot
d) All of the mentioned
Answer: a
Clarification: Pivot (sum(quantity) for color in (’dark’,’pastel’,’white’)).
7.
{ (item name, color, clothes size), (item name, color), (item name, clothes size), (color, clothes size), (item name), (color), (clothes size), () }
This can be achieved by using which of the following ?
a) group by rollup
b) group by cubic
c) group by
d) none of the mentioned
Answer: d
Clarification: ‘Group by cube’ is used .
8. What do data warehouses support?
a) OLAP
b) OLTP
c) OLAP and OLTP
d) Operational databases
Answer: a
Clarification: None.
9.
SELECT item name, color, clothes SIZE, SUM(quantity) FROM sales GROUP BY rollup(item name, color, clothes SIZE);
How many grouping is possible in this rollup?
a) 8
b) 4
c) 2
d) 1
Answer: b
Clarification: { (item name, color, clothes size), (item name, color), (item name), () }.
10. Which one of the following is the right syntax for DECODE?
a) DECODE (search, expression, result [, search, result]… [, default])
b) DECODE (expression, result [, search, result]… [, default], search)
c) DECODE (search, result [, search, result]… [, default], expression)
d) DECODE (expression, search, result [, search, result]… [, default])
Answer: d