In psql, which command lists all tables in the currently connected database?
1. In psql, which command lists all tables in the currently connected database?
- A.\dt
- B.\lt
- C.\show tables
- D.\d tables
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PostgreSQL - Basics
Database backups, psql commands, table modification, dropping databases, and string functions.
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Which SQL statement is used to create a new database in PostgreSQL?
2. Which SQL statement is used to create a new database in PostgreSQL?
- A.CREATE DATABASE <name>;
- B.ADD DATABASE <name>;
- C.NEW DATABASE <name>;
- D.INIT DATABASE <name>;
What is the legacy PostgreSQL-specific data type alias used to create auto-incrementing integer columns?
3. What is the legacy PostgreSQL-specific data type alias used to create auto-incrementing integer columns?
- A.SERIAL
- B.AUTO_INCREMENT
- C.IDENTITY
- D.SEQUENCE
Which SQL clause is used to limit the number of rows returned by a SELECT query in PostgreSQL?
4. Which SQL clause is used to limit the number of rows returned by a SELECT query in PostgreSQL?
- A.LIMIT
- B.TOP
- C.ROWCOUNT
- D.TAKE
Which data type in PostgreSQL is best suited for storing long, arbitrary-length text strings without a specific size limit?
5. Which data type in PostgreSQL is best suited for storing long, arbitrary-length text strings without a specific size limit?
- A.TEXT
- B.VARCHAR(255)
- C.CHAR
- D.STRING
What is PostgreSQL?
6. What is PostgreSQL?
- A.An open-source object-relational database management system
- B.A NoSQL key-value caching server
- C.A frontend web application server
- D.A cloud file storage hosting platform
What is the recommended modern way to define an auto-incrementing integer primary key column in PostgreSQL (PostgreSQL 10+)?
7. What is the recommended modern way to define an auto-incrementing integer primary key column in PostgreSQL (PostgreSQL 10+)?
- A.GENERATED BY DEFAULT AS IDENTITY
- B.AUTO_INCREMENT
- C.SERIAL PRIMARY KEY ONLY
- D.IDENTITY(1,1)
What is the name of the official command-line terminal client interface for PostgreSQL?
8. What is the name of the official command-line terminal client interface for PostgreSQL?
- A.psql
- B.pgAdmin
- C.postgres-cli
- D.sql-terminal
In psql, how do you exit the interactive command line utility?
9. In psql, how do you exit the interactive command line utility?
- A.\q
- B.\exit
- C.\quit
- D.\close
What does a CHECK constraint do in a PostgreSQL table definition?
10. What does a CHECK constraint do in a PostgreSQL table definition?
- A.It enforces that values in a column satisfy a boolean expression or condition.
- B.It checks if the database is online and connected.
- C.It verifies that a column references a valid primary key.
- D.It ensures that a column cannot contain duplicate values.
In psql, which command is used to connect to a specific database?
11. In psql, which command is used to connect to a specific database?
- A.\c <database_name>
- B.\connect_to <database_name>
- C.\use <database_name>
- D.\l <database_name>
In the psql command-line client, which command lists all available databases in the server?
12. In the psql command-line client, which command lists all available databases in the server?
- A.\l
- B.\d
- C.\dt
- D.\c
How do you specify that NULL values should appear first in the sorted output of a SELECT query in PostgreSQL?
13. How do you specify that NULL values should appear first in the sorted output of a SELECT query in PostgreSQL?
- A.ORDER BY <column> NULLS FIRST
- B.ORDER BY <column> WITH NULLS
- C.ORDER BY NULLS, <column>
- D.ORDER BY <column> DEFAULT NULLS
Which SQL clause is used to skip a specific number of rows before returning query results in PostgreSQL?
14. Which SQL clause is used to skip a specific number of rows before returning query results in PostgreSQL?
- A.OFFSET
- B.SKIP
- C.LIMIT FROM
- D.START AT
How do you write a multi-line comment in PostgreSQL SQL scripts?
15. How do you write a multi-line comment in PostgreSQL SQL scripts?
- A.By enclosing the comment block in /* and */
- B.By prefixing each line with #
- C.By prefixing each line with --
- D.By enclosing the block in <!-- and -->
Which SQL-standard boolean values does the BOOLEAN data type accept in PostgreSQL inserts?
16. Which SQL-standard boolean values does the BOOLEAN data type accept in PostgreSQL inserts?
- A.TRUE and FALSE (along with variants like 't', 'f', '1', '0')
- B.YES and NO only
- C.Only integer values 1 and -1
- D.Any non-empty string value
Which SQL command is used to remove a column from an existing table in PostgreSQL?
17. Which SQL command is used to remove a column from an existing table in PostgreSQL?
- A.ALTER TABLE <table_name> DROP COLUMN <column_name>;
- B.ALTER TABLE <table_name> REMOVE <column_name>;
- C.ALTER TABLE <table_name> DELETE COLUMN <column_name>;
- D.MODIFY TABLE <table_name> DROP <column_name>;
What is the difference between the CHAR and VARCHAR data types in PostgreSQL?
18. What is the difference between the CHAR and VARCHAR data types in PostgreSQL?
- A.CHAR pads values with spaces to reach a fixed length; VARCHAR stores variable-length strings without padding.
- B.CHAR stores numbers; VARCHAR stores text characters.
- C.CHAR is unlimited in size; VARCHAR has a 255-character limit.
- D.CHAR is open-source; VARCHAR is a proprietary data type.
What is pgAdmin?
19. What is pgAdmin?
- A.A graphical web/desktop administration tool for managing PostgreSQL
- B.The default command-line client built into PostgreSQL
- C.A database server configuration file stored in the host system
- D.A software library used to run database replication clusters
Which operator is used for string concatenation in PostgreSQL?
20. Which operator is used for string concatenation in PostgreSQL?
- A.||
- B.+
- C.CONCAT
- D.&
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