Datamatics Global Services ETL Developer Interview Questions and Answers

Q1. Basic Question Answer
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Q2. Basic SQL , SNWOFLAKE AND ETL Concepts
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Q1. Run time polymorphism code
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Q2. Linked list code
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Q3. Deep copy shallow copy differences
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Deep copy creates a new copy of an object with its own unique memory space, while shallow copy creates a new object that references the same memory locations as the original object.
• Deep copy duplicates all nested objects, while shallow copy only duplicates the references to nested objects.

• Deep copy ensures that changes to the copied object do not affect the original object, while shallow copy may lead to unintended sid...read more
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Q1. More deep questions about polymorphism code
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Q2. Code for interchange of strings without strcpy
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Use a loop to swap characters of two strings without using strcpy function.
• Create two arrays of characters to store the strings

• Use a loop to iterate through each character of the strings and swap them

• Ensure to handle cases where strings have different lengths
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Q1. What are Types of joins
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Types of joins in SQL are Inner Join, Left Join, Right Join, and Full 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 Join: Returns rows when there is a match in one of the tables.
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Q2. Difference between groupby and having clause
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GROUP BY is used to group rows that have the same values into summary rows, while HAVING is used to filter groups based on a specified condition.
• GROUP BY is used with aggregate functions to group the result set by one or more columns.

• HAVING is used to filter groups based on a specified condition after the GROUP BY clause.

• GROUP BY is used before the HAVING clause in a query.

• Example: SELECT department, COUNT(*) FROM empl
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Q3. What are DML commands
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DML commands are Data Manipulation Language commands used to manage data in a database.
• DML commands include INSERT, UPDATE, DELETE, and SELECT.

• INSERT is used to add new rows of data into a table.

• UPDATE is used to modify existing data in a table.

• DELETE is used to remove rows of data from a table.

• SELECT is used to retrieve data from a database.
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Q4. Difference between Primary key and Unique key
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Primary key uniquely identifies each record in a table, while Unique key allows only one instance of a value in a column.
• Primary key does not allow NULL values, while Unique key allows one NULL value.

• Primary key automatically creates a clustered index, while Unique key creates a non-clustered index by default.

• Primary key can be referenced by foreign keys, while Unique key cannot be referenced by foreign keys.
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Q5. What are Index and types of index
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Indexes are data structures that improve the speed of data retrieval operations in a database.
• Indexes are used to quickly locate data without having to search every row in a database table.

• Types of indexes include clustered, non-clustered, unique, and composite indexes.

• Clustered indexes determine the physical order of data in a table, while non-clustered indexes store a separate copy of the indexed columns.

• Unique index...read more
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Q6. What is execution plan
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Execution plan is a roadmap that SQL Server uses to execute a query, showing the steps taken to retrieve data.
• Execution plan is generated by the query optimizer to determine the most efficient way to execute a query.

• It shows the order in which tables are accessed, joins are performed, and filters are applied.

• Execution plan can be viewed using tools like SQL Server Management Studio or by using the EXPLAIN statement in
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Q7. Explain about your Project ? challenges faced
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Q8. Write a sql query depart wise max salary
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SQL query to retrieve the maximum salary for each department
• Use the MAX() function to find the maximum salary

• Group the results by department using the GROUP BY clause

• Join the employee table with the department table to get the department information
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Q9. Given a table TEAM with only one column teamname, write a sql query where each team play with each other , no duplicate match
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Q10. Provide o/p for innerjoin, left join, right join, cross join on a(1,1,1,2,2,3) b(1,1,2,4)
Ans. 
Different types of SQL joins with given data sets a and b.
• Inner join: Returns rows where there is a match in both tables (1,1)

• Left join: Returns all rows from the left table and the matched rows from the right table (1,1,1,2,2)

• Right join: Returns all rows from the right table and the matched rows from the left table (1,1,2,4)

• Cross join: Returns the Cartesian product of the two tables (1,1,1,1,1,2,1,4,1,1,2,1,2,2,1,4,2,...read more
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Q11. Row_number, rank, dense_rank with example
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row_number, rank, dense_rank are window functions in SQL used to assign a unique number to each row based on specified criteria.
• row_number() assigns a unique sequential integer starting from 1 to each row in the result set

• rank() assigns a unique rank to each row based on the specified ordering criteria, with gaps in ranking for ties

• dense_rank() assigns a unique rank to each row based on the specified ordering criteria,
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Q12. What is trigger
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A trigger is a special type of stored procedure that automatically executes when certain events occur in a database.
• Triggers can be used to enforce business rules, maintain referential integrity, and automate repetitive tasks.

• Examples of trigger events include INSERT, UPDATE, and DELETE operations on a table.

• Triggers can be defined to execute before or after the triggering event.
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Q13. Diffrenc between function and store procedure
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Functions return a value, while stored procedures do not. Functions can be used in SELECT statements, stored procedures cannot.
• Functions return a single value, while stored procedures can return multiple values or none at all.

• Functions can be used in SELECT statements to return a value, while stored procedures cannot be used in this way.

• Functions can be called from within stored procedures, but stored procedures cannot
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Q1. What is the difference between volatile and atomic variables?
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Q2. How can caching be implemented?
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Database Management system SQL and PlSQL

Database Base Management system SQL and PlSQL

Database Management system

Database Management system

Database Management system

Database Management system

Database Base Management system

Q1. Database Management system
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Q2. SQL and PlSQL Mango Data And Manu Database Management system
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Q3. C Language and C++Language and Java
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Q4. Data Analysis and Data entry
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Q5. DBMS C,C++ Java Data Entry Ms Excel Ms Word Ms PP
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Q1. Ask for basic dot net questions
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Basic core java, reasoning,english

Dsa question of arrays

Q1. Tell me about yourself
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I am a passionate software developer with experience in Java, Python, and web development.
• Experienced in Java, Python, and web development technologies

• Strong problem-solving skills

• Team player with excellent communication skills
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Q2. Stacks and queues
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Q3. Time complexity
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Q1. Query Builder, Workflow, Scheduler
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Q2. Sling Model, Servlet, OSGi , Component, Template
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Q1. Core Values, weakness
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Q2. How do you handle pressure
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I handle pressure by staying organized, prioritizing tasks, and taking breaks when needed.
• I prioritize tasks based on deadlines and importance

• I break down complex tasks into smaller, manageable steps

• I communicate with team members and managers about workload and deadlines

• I practice stress-relief techniques such as deep breathing or taking short walks
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