SQL and PostgreSQL Quiz

To pass the quiz, you must correctly answer at least 18 of the 20 questions below. # --quizzes-- ## --quiz-- ### --question-- #### --text-- What is a relational database? #### --distractors-- A database structured to recognize non-relation between stored items. --- A database that stores unstructured data. --- A flat file-based system. #### --answer-- A database structured to recognize and manage relationships between data in tables. ### --question-- #### --text-- How does a non-relational database differ from a relational database? #### --distractors-- Non-relational databases use tables, while relational databases do not. --- Relational databases can store unstructured data. --- Non-relational databases are slower than relational databases. #### --answer-- Non-relational databases can store unstructured data. ### --question-- #### --text-- What does the `\l` command do when executed in the PostgreSQL interactive terminal (`psql`)? #### --distractors-- Lists all schemas. --- Lists all tables. --- Connects to a database. #### --answer-- Lists all databases. ### --question-- #### --text-- Which of the following commands creates a new table in SQL? #### --distractors-- `ADD TABLE` --- `NEW TABLE` --- `ALTER TABLE` #### --answer-- `CREATE TABLE` ### --question-- #### --text-- What is the purpose of a foreign key in a relational database? #### --distractors-- To allow duplication of data. --- To uniquely identify a row in the table. --- To store large amounts of text data. #### --answer-- To create a relationship between two tables. ### --question-- #### --text-- Which command will add a new column to an existing table? #### --distractors-- `ADD COLUMN column_name TO table_name data_type;` --- `INSERT COLUMN column_name INTO table_name data_type;` --- `MODIFY TABLE table_name ADD COLUMN column_name data_type;` #### --answer-- `ALTER TABLE table_name ADD COLUMN column_name data_type;` ### --question-- #### --text-- What type of relationship exists when one record in Table A corresponds to one or more records in Table B? #### --distractors-- One-to-One (1-1) --- Many-to-Many (m-m) --- Many-to-one(m-1) #### --answer-- One-to-Many (1-m) ### --question-- #### --text-- What is a query? #### --distractors-- A request to remove all data from the database. --- A special row for unique values in a database. --- A special column for unique values in a database. #### --answer-- A request for specific data from the database. ### --question-- #### --text-- How do you delete a column from a table in SQL? #### --distractors-- `REMOVE COLUMN column_name FROM table_name;` --- `DELETE COLUMN column_name FROM table_name;` --- `MODIFY TABLE table_name DELETE column_name;` #### --answer-- `ALTER TABLE table_name DROP COLUMN column_name;` ### --question-- #### --text-- What is the function of the `PRIMARY KEY` constraint in SQL? #### --distractors-- To link two tables together. --- To define the default value for a column. --- To allow null values in the column. #### --answer-- To ensure that the column contains unique values. ### --question-- #### --text-- What does the command `\c` do in the PostgreSQL interactive terminal (`psql`)? #### --distractors-- Lists all tables in the current database. --- Displays the current database connection details. --- Exits the `psql` shell. #### --answer-- Connects to the specified database. ### --question-- #### --text-- What is a composite key in a relational database? #### --distractors-- A key that is derived from another key. --- A key that changes frequently based on data updates. --- A key used exclusively for foreign key relationships. #### --answer-- A key that is composed of multiple columns to uniquely identify a record. ### --question-- #### --text-- Which command inserts data into a table? #### --distractors-- `PUT VALUES` --- `UPDATE INTO` --- `ADD DATA` #### --answer-- `INSERT INTO` ### --question-- #### --text-- How do you rename a column in SQL? #### --distractors-- `MODIFY COLUMN` --- `CHANGE COLUMN` --- `ALTER COLUMN` #### --answer-- `RENAME COLUMN` ### --question-- #### --text-- Which query will delete all records from the employees table? #### --distractors-- `REMOVE ALL` --- `TRUNCATE employees` --- `DROP RECORDS` #### --answer-- `DELETE FROM employees` ### --question-- #### --text-- Which SQL constraint specifically ensures that a column can contain only unique values, allowing nulls? #### --distractors-- `NOT NULL` --- `FOREIGN KEY` --- `PRIMARY KEY` #### --answer-- `UNIQUE` ### --question-- #### --text-- Which of the following is NOT an example of a commonly used relational database in the industry? #### --distractors-- MySQL --- SQLite --- PostgreSQL #### --answer-- SQLQuery ### --question-- #### --text-- What does a one-to-one (1-1) relationship represent in a relational database? #### --distractors-- Each record in Table A corresponds to one or more records in Table B. --- Each record in Table A corresponds to no records in Table B. --- Each record in Table A corresponds to multiple records in Table B and vice versa. #### --answer-- Each record in Table A corresponds to exactly one record in Table B. ### --question-- #### --text-- What command will list all tables in the current PostgreSQL database? #### --distractors-- `\l` --- `SHOW TABLES` --- `\t` #### --answer-- `\d` ### --question-- #### --text-- Which of the following allows you to join a table with itself? #### --distractors-- `LEFT OUTER JOIN` --- `CROSS JOIN` --- `RIGHT OUTER JOIN` #### --answer-- `SELF JOIN`