УПР 91-120

What is the main advantage of using an index in a database?

• It reduces storage requirements

• It prevents duplicate record

• It speeds up query execution

• It improves data integrity

What is the purpose of a foreign key in a relational database?

• To enforce uniqueness in a table

• To store temporary data

• To establish relationships between tables

• To improve performance of SELECT queries

Which SQL clause is used to filter results after aggregation?

• WHERE

• ORDER BY

• HAVING

• GROUP BY

What is the difference between INNER JOIN and LEFT JOIN?

• INNER JOIN includes all rows from both tables

• LEFT JOIN returns only matching rows from both tables

• LEFT JOIN returns all rows from the left table and matching rows from the right table

• INNER JOIN is used only for one-to-one relationships

What is the purpose of normalization in databases?

• To store data in a single table

• To speed up all queries

• To reduce data redundancy and improve consistency

• To avoid using indexes

Which command is used to list all databases in postgresql?

• SHOW DATABASES;

• SELECT * FROM pg_databases;

• \l

• DESCRIBE DATABASES;

What is the purpose of the EXPLAIN ANALYZE command in postgresql?

• To list all tables in a database

• To create a new index

• To show the execution plan and performance details of a query

• To modify an existing table

In pgadmin, what is the function of the Query Tool?

• To visualize database schemas

• To create new user roles

• To write and execute SQL queries

• To perform database backups

What is the advantage of using a materialized view in postgresql?

• It prevents SQL injection attacks

• It allows updates to be applied instantly

• It stores query results for faster retrieval

• It replaces indexes

What is the purpose of a tablespace in postgresql?

• To store backup data

• To define user permissions

• To control where database objects are stored on disk

• To improve query execution speed