Ernst & Young Data Engineer Interview Questions, Process, and Tips

Q1. Sql order of execution
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SQL order of execution determines the sequence in which different clauses are processed in a query.
• SQL query is parsed and validated first

• Next, the query optimizer creates an execution plan

• Execution plan includes steps like table scans, index scans, joins, etc.

• Finally, the query is executed and results are returned
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Q2. Sql question on finding highest salary for each employee where employees and department table are given in each department.
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Q1. Maximum salary for each department in sql
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Q1. Difference between star and Snowflake schema in detail
Ans. 
Star schema has a single fact table connected to multiple dimension tables, while Snowflake schema has normalized dimension tables.
• Star schema denormalizes data for faster query performance

• Snowflake schema normalizes data to reduce redundancy

• Star schema is easier to understand and query

• Snowflake schema is more flexible and scalable

• Example: A star schema for a sales database would have a fact table for sales transaction...read more
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Q2. Diff btw transient table , fact table and dimension table
Ans. 
Transient tables are temporary tables, fact tables contain quantitative data, and dimension tables contain descriptive data.
• Transient tables are temporary and used for intermediate processing or storing temporary data.

• Fact tables contain quantitative data such as sales, revenue, or quantities.

• Dimension tables contain descriptive data like customer names, product categories, or dates.
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