ETL Testing Engineer Interview Questions and Answers

To get the sum of consecutive numbers in a table, you can use SQL queries with aggregate functions like SUM() and window functions like ROWS BETWEEN.

• Use the SUM() function to calculate the sum of consecutive numbers in a column.

• Use window functions like ROWS BETWEEN to define the range of consecutive numbers.

• Combine the SUM() function with window functions to get the desired result.

• Here's an example query: SELECT SUM(column_name) OVER (ORDER BY column_name ROWS BETWEEN 1 PREC...read more

DROP and DELETE are SQL commands used to remove data or objects from a database.

• DROP command is used to remove an entire table or database object from the database.

• DELETE command is used to remove specific rows or records from a table based on a condition.

• DROP command is a DDL (Data Definition Language) command, while DELETE command is a DML (Data Manipulation Language) command.

• Examples: DROP TABLE employees; DELETE FROM customers WHERE age > 50;

Union is used to combine the result sets of two or more SELECT statements into a single result set.

• Union is used to combine rows from two or more tables into a single result set.

• The number of columns and their data types must be the same in all SELECT statements.

• Duplicate rows are eliminated in the result set of UNION.

• UNION ALL is similar to UNION, but it does not eliminate duplicate rows.