Bindu Interview Questions, Process, and Tips

Union and Union All are SQL commands used to combine the result sets of two or more SELECT statements.

• Union is used to combine the result sets of two or more SELECT statements, removing duplicates.

• Union All is used to combine the result sets of two or more SELECT statements, including duplicates.

• Union and Union All require that the number of columns in each SELECT statement is the same.

• Example: SELECT column1 FROM tabl...read more

Rank is the position of an element in a sorted list, while dense rank is the position of an element in a sorted list with no gaps between ranks.

• Rank assigns unique numbers to each element based on their order in a sorted list.

• Dense rank also assigns unique numbers to each element, but without any gaps between ranks.

• For example, if we have a list of numbers [10, 20, 20, 30], the rank of 20 would be 2 and the dense rank ...read more

ETL validations ensure data accuracy, completeness, and consistency during the extraction, transformation, and loading process.

• Schema validation to ensure data types and formats are correct

• Data completeness checks to verify all expected data is present

• Duplicate data detection to prevent redundancy

• Referential integrity checks to maintain relationships between tables

• Data quality checks to identify anomalies or errors

To find duplicates in an array of strings

• Iterate through the array and store each element in a HashSet

• If the element is already in the HashSet, it is a duplicate

• Alternatively, sort the array and compare adjacent elements for duplicates