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What’s the difference between using WHERE versus HAVING? WHERE id used for filtering records. HAVING is used with aggregate function because WHERE keyword cannot be used with aggregate function.

If I want to track historical changes for a given dimensional data, what type of Slowly Changing Dimension should we be implementing Type 4: Using Historical Table

Explain the difference between an inner join and outer join using an example. INNER JOIN: it selects data that have matching values in both tables. OUTER JOIN: return all data when there is match in either left or right table.

DISTINCT vs GROUP BY: when would you use each + what is the commonality DISTINCT: for getting only distinct values. GROUP BY: it groups rows that have the same values into summary rows.

What is Primary Key and Foreign key in a table (answer to this question exposes data modeling expertise) Primary key: it uniquely identifies each record in table. Contains UNIQUE vales and cannot be NULL Foreign Key: it is used for preventing actions that would destroy links between tables. Field in one table that refers to the Primary Key in another table.

Python:

Is python case sensitive? Yes

Is indentation required in python? If yes, why? Yes, for defining the block of statement

How will you convert a string to all lowercase? .lower()

What is a dictionary in Python, and can you give an example? It is used for storing data value in key:value pairs. A={“Apple”:Red, ”Ball”:”Blue”, ”Car”:”White”, “Value”: 1234}

What are the different data structures in Python? List, tuple, set, dictionary

What is the difference between list and set? List: mutable (elementwise/list itself) can have duplicates, ordered Set: mutable (elements in the sets are immutable), can’t have duplicates, unordered

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Candidate Pre-Screen Answers

SQL

1. What’s the difference between using WHERE versus HAVING?

WHERE id used for filtering records.

HAVING is used with aggregate function because WHERE keyword cannot be

used with aggregate function.

2. If I want to track historical changes for a given dimensional data, what type of Slowly

Changing Dimension should we be implementing

Type 4: Using Historical Table

3. Explain the difference between an inner join and outer join using an example.

INNER JOIN: it selects data that have matching values in both tables.

OUTER JOIN: return all data when there is match in either left or right table.

4. DISTINCT vs GROUP BY: when would you use each + what is the commonality

DISTINCT: for getting only distinct values.

GROUP BY: it groups rows that have the same values into summary rows.

5. What is Primary Key and Foreign key in a table (answer to this question exposes data

modeling expertise)

Primary key: it uniquely identifies each record in table. Contains UNIQUE vales

and cannot be NULL

Foreign Key: it is used for preventing actions that would destroy links between

tables. Field in one table that refers to the Primary Key in another table.

Python:

1. Is python case sensitive?

Yes

2. Is indentation required in python? If yes, why?

Yes, for defining the block of statement

3. How will you convert a string to all lowercase?

.lower()

4. What is a dictionary in Python, and can you give an example?

It is used for storing data value in key:value pairs.

A={“Apple”:Red, ”Ball”:”Blue”, ”Car”:”White”, “Value”: 1234}

5. What are the different data structures in Python?

List, tuple, set, dictionary

6. What is the difference between list and set?

List: mutable (elementwise/list itself) can have duplicates, ordered

Set: mutable (elements in the sets are immutable), can’t have duplicates,

unordered

Research Development And Data Analysis (EDUC 555)

Capital University, Columbus Ohio

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