PostgreSQL, often referred to as Postgres, is a powerful open-source relational database management system (RDBMS) known for its scalability, robustness, and extensibility. It offers advanced features like ACID compliance, support for complex data types, and support for both SQL and NoSQL data. PostgreSQL is highly regarded for its performance, security, and reliability, making it a popular choice for applications ranging from small startups to large enterprises. Its active developer community continuously enhances and maintains the software. PostgreSQL is an excellent choice for data storage, analysis, and management in various domains, including web applications, data warehousing, and geospatial applications.
21. How do you retrieve all columns from a table named "employees" in PostgreSQL?
22. Which SQL statement is used to filter rows in a table based on a specified condition?
23. How can you sort the result set of a query in ascending order by a specific column in PostgreSQL?
24. What is the SQL keyword used to eliminate duplicate rows from a result set?
25. Which SQL statement is used to insert new records into a table in PostgreSQL?
26. How do you update existing records in a PostgreSQL table?
27. What is the purpose of the SQL "DELETE" statement in PostgreSQL?
28. What SQL operator is used to combine the result sets of two or more SELECT statements in PostgreSQL?
29. How can you retrieve only the first 'n' rows from a result set in PostgreSQL?
30. What is the SQL clause used to group rows based on the values of a specific column in PostgreSQL?