Eucloid Data Solutions Interview Questions, Process, and Tips

Q1. Write SQL aggregation and join queries.
Ans. 
SQL aggregation and join queries for data analysis.
• Use GROUP BY clause for aggregation

• Use aggregate functions like SUM, AVG, COUNT, etc.

• Use JOIN clause to combine data from multiple tables
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Q2. Name types of joins and explain them.
Ans. 
Types of joins in SQL include inner join, left join, right join, and full outer join.
• Inner join: Returns rows when there is a match in both tables.

• Left join: Returns all rows from the left table and the matched rows from the right table.

• Right join: Returns all rows from the right table and the matched rows from the left table.

• Full outer join: Returns all rows when there is a match in either table.
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Q3. How would you import data in power bi using api?
Ans. 
You can import data in Power BI using API by connecting to the API endpoint and specifying the required parameters.
• Use the 'Get Data' option in Power BI to connect to the API endpoint

• Specify the required authentication method (e.g. API key, OAuth)

• Select the data you want to import and transform it as needed

• Refresh the data periodically to keep it up to date
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Q4. Extract number from stings in sql
Ans. 
Extract numbers from strings in SQL
• Use the SQL function REGEXP_REPLACE to remove non-numeric characters

• Use the SQL function REGEXP_SUBSTR to extract numbers from strings

• Consider using regular expressions to handle different number formats
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Q1. What are window functions in sql and explain in detail
Ans. 
Window functions in SQL are used to perform calculations across a set of table rows related to the current row.
• Window functions operate on a set of rows related to the current row

• They can be used to calculate running totals, ranks, and averages

• Common window functions include ROW_NUMBER(), RANK(), DENSE_RANK(), and NTILE()

• They are typically used with the OVER() clause to define the window frame
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Q2. Difference between joins
Ans. 
Joins are used to combine rows from two or more tables based on a related column between them.
• Inner Join: Returns rows when there is a match in both tables.

• Left Join: Returns all rows from the left table and the matched rows from the right table.

• Right Join: Returns all rows from the right table and the matched rows from the left table.

• Full Outer Join: Returns rows when there is a match in either table.

• Cross Join: Retur
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Q3. What is order of execution in sql
Ans. 
Order of execution in SQL refers to the sequence in which different clauses are processed in a SQL query.
• 1. FROM clause is processed first to retrieve data from the specified tables.

• 2. WHERE clause is processed next to filter the rows based on specified conditions.

• 3. GROUP BY clause is processed to group the rows based on specified columns.

• 4. HAVING clause is processed to filter the grouped rows based on specified cond...read more
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Q4. Ways to write time efficient sql queries
Ans. 
Use indexes, limit columns in SELECT, avoid using SELECT *, optimize joins
• Use indexes on columns frequently used in WHERE clauses

• Limit columns in SELECT to only those needed

• Avoid using SELECT * to retrieve all columns

• Optimize joins by using INNER JOIN instead of OUTER JOIN when possible
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Q1. What are SQL joins
Ans. 
SQL joins are used to combine rows from two or more tables based on a related column between them.
• SQL joins are used to retrieve data from multiple tables based on a related column between them

• Types of SQL joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

• INNER JOIN returns rows when there is at least one match in both tables

• LEFT JOIN returns all rows from the left table and the matched rows from the right ...read more
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Q2. What are the different window functions?
Ans. 
Window functions are used to perform calculations across a set of table rows related to the current row.
• Window functions include ROW_NUMBER, RANK, DENSE_RANK, NTILE, LAG, LEAD, FIRST_VALUE, LAST_VALUE, and more

• They allow for calculations to be performed on a specific subset of rows within a query result set

• Window functions are commonly used in analytical queries to calculate running totals, moving averages, and more
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Q1. How will you identify the given two strings as anagram?
Ans. 
Anagrams are two strings that have the same characters in a different order.
• Check if the two strings have the same length.

• Sort the characters in both strings and compare if they are equal.

• Alternatively, count the frequency of characters in both strings and compare the counts.
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Q2. From a table with employee details and another table with order details, count the employees who ordered all the category items.
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Q1. SQL queries were asked
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Q2. Cohort analysis, average order value SQL questions
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Q1. Case study round, puzzles
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Q2. Question about ongoing project
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Sql questions and queries were asked and also made to write the pseduo code along with case studies

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