PostgreSQL DATE Functions Quiz: Test Your SQL Knowledge

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True / False

In PostgreSQL, the CURRENT_DATE function returns the current date.

True False

CURRENT_DATE is a standard SQL function supported by PostgreSQL that returns the current date as a date value.

True / False

In PostgreSQL, the AGE function can calculate the difference between two dates.

True False

The AGE function in PostgreSQL is used to calculate the interval between two dates, providing a precise difference.

True / False

In PostgreSQL, the DATE_PART function can extract parts of a date, such as the year or month.

True False

The DATE_PART function in PostgreSQL allows you to extract specific parts of a date, such as the year, month, day, hour, etc.

True / False

In PostgreSQL, the EXTRACT function cannot be used to retrieve the day of the week from a date.

True False

The EXTRACT function in PostgreSQL can be used to retrieve various parts of a date, including the day of the week.

True / False

In PostgreSQL, the DATE_TRUNC function can be used to truncate a date to a specified precision, like 'month' or 'year'.

True False

The DATE_TRUNC function in PostgreSQL truncates a date or timestamp to the specified precision (e.g., 'month', 'year').

True / False

In PostgreSQL, the TO_DATE function converts a text string to a date using a specified format.

True False

The TO_DATE function in PostgreSQL converts a text string to a date value based on the format specified in the function's arguments.

True / False

In PostgreSQL, the ISODOW keyword in the EXTRACT function returns the ISO 8601 day of the week.

True False

The ISODOW keyword in the EXTRACT function returns the ISO 8601 day of the week, where Monday is 1 and Sunday is 7.

True / False

In PostgreSQL, the INTERVAL keyword can only be used with TIMESTAMP types and not DATE types.

True False

The INTERVAL keyword in PostgreSQL can be used with both TIMESTAMP and DATE types to add or subtract intervals.

True / False

In PostgreSQL, the JUSTIFY_INTERVAL function adjusts intervals to ensure that the months and days are within their normal ranges.

True False

The JUSTIFY_INTERVAL function in PostgreSQL adjusts an interval to ensure that the months and days components are within their normal ranges (e.g., not having 30 days in February).

Q10

True / False

In PostgreSQL, the TIMEZONE function can convert a TIMESTAMP with time zone to another time zone.

True False

The TIMEZONE function in PostgreSQL converts a TIMESTAMP WITH TIME ZONE to another time zone, adjusting the time accordingly.

Q11

Single Choice

Which PostgreSQL function is used to get the current date?

NOW() CURRENT_DATE CURRENT_TIMESTAMPDATE_TRUNC

In PostgreSQL, CURRENT_DATE returns the current date with no time information.

Q12

Single Choice

How do you add 7 days to the current date in PostgreSQL?

SELECT CURRENT_DATE + INTERVAL '7 DAYS'; SELECT ADD_DATE(CURRENT_DATE, 7); SELECT DATE_ADD(CURRENT_DATE, INTERVAL 7 DAY);SELECT CURRENT_DATE + 7;

The correct way to add a specific number of days to a date in PostgreSQL is by using the INTERVAL keyword.

Q13

Single Choice

Which function in PostgreSQL can extract the year from a date column?

YEAR() EXTRACT(YEAR FROM date_column) DATE_PART('year', date_column)YEAR_PART(date_column)

DATE_PART extracts a subfield (e.g., year, month, day) from a date in PostgreSQL.

Q14

Single Choice

How would you get the difference in days between two dates in PostgreSQL?

SELECT DATEDIFF(date1, date2); SELECT DATE_PART('day', date2 - date1); SELECT date2 - date1;SELECT DATE_DIFF(date1, date2);

In PostgreSQL, subtracting two dates directly gives the difference in days.

Q15

Single Choice

What is the correct way to extract the week number from a date in PostgreSQL?

SELECT WEEK(date_column); SELECT EXTRACT(WEEK FROM date_column); SELECT WEEKNUMBER(date_column);SELECT DATE_PART('week', date_column);

DATE_PART('week', date_column) returns the week number of the year in PostgreSQL.

Q16

Single Choice

How can you format a date in PostgreSQL to display as 'YYYY-MM-DD'?

SELECT FORMAT(date_column, 'YYYY-MM-DD'); SELECT TO_CHAR(date_column, 'YYYY-MM-DD'); SELECT DATE_FORMAT(date_column, 'YYYY-MM-DD');SELECT FORMAT_DATE('YYYY-MM-DD', date_column);

The TO_CHAR function in PostgreSQL formats the date according to the specified format string.

Q17

Single Choice

Which PostgreSQL function can return the last day of the month for a given date?

LAST_DAY() END_OF_MONTH(date_column) SELECT DATE_TRUNC('month', date_column) + INTERVAL '1 MONTH - 1 day';SELECT LAST_DAY_OF_MONTH(date_column);

This query uses DATE_TRUNC to get the first day of the month and adds an interval of one month minus one day to get the last day.

Q18

Single Choice

How do you calculate the number of months between two dates in PostgreSQL?

SELECT MONTHS_BETWEEN(date1, date2); SELECT DATE_PART('month', AGE(date1, date2)); SELECT EXTRACT(MONTH FROM (date2 - date1));SELECT EXTRACT('month' FROM AGE(date1, date2));

AGE function returns the interval between two dates, and DATE_PART extracts the month part from it.

Q19

Single Choice

Which function returns the ISO week date in PostgreSQL?

SELECT TO_CHAR(date_column, 'IW'); SELECT EXTRACT(ISO_WEEK FROM date_column); SELECT DATE_PART('isoweek', date_column);SELECT TO_DATE(date_column, 'IW');

DATE_PART('isoweek', date_column) returns the ISO week number from a date.

Q20

Single Choice

How do you find the number of days in the month of a specific date in PostgreSQL?

SELECT DAYS_IN_MONTH(date_column); SELECT EXTRACT(DAY FROM (date_trunc('month', date_column) + interval '1 month - 1 day')); SELECT EXTRACT(DAYS FROM date_column);SELECT DATE_PART('days', date_column);

This query uses DATE_TRUNC to get the first day of the month and then calculates the number of days in that month by adding an interval of one month minus one day and extracting the day part.

Q21

Multiple Choice

Which SQL queries correctly use the CURRENT_DATE function to retrieve the current date in PostgreSQL?

SELECT * FROM orders WHERE order_date = CURRENT_DATE; SELECT * FROM orders WHERE order_date = 'CURRENT_DATE'; SELECT * FROM orders WHERE order_date = NOW();SELECT * FROM orders WHERE order_date = CURRENT_TIMESTAMP;

The CURRENT_DATE function returns the current date. It is useful for filtering records based on the current date.

Q22

Multiple Choice

Which SQL queries correctly use the EXTRACT function to retrieve parts of a date in PostgreSQL?

SELECT EXTRACT(YEAR FROM birth_date) AS birth_year FROM employees; SELECT EXTRACT(MONTH FROM birth_date) AS birth_month FROM employees; SELECT EXTRACT(DAY FROM birth_date) AS birth_day FROM employees;SELECT EXTRACT(HOUR FROM birth_date) AS birth_hour FROM employees;

The EXTRACT function is used to extract parts of a date, such as the year, month, or day, from a date or timestamp.

Q23

Multiple Choice

Which SQL queries correctly use the AGE function to calculate the age in PostgreSQL?

SELECT AGE(date_of_birth) AS age FROM members; SELECT AGE(CURRENT_DATE, date_of_birth) AS age FROM members; SELECT AGE(date_of_birth, CURRENT_DATE) AS age FROM members;SELECT AGE('date_of_birth') AS age FROM members;

The AGE function is used to calculate the age based on two dates. It is typically used to calculate the age of a person or duration between two dates.

Q24

Multiple Choice

Which SQL queries correctly use the DATE_TRUNC function to truncate a date or timestamp in PostgreSQL?

SELECT DATE_TRUNC('hour', event_timestamp) AS truncated_time FROM events; SELECT DATE_TRUNC('day', event_timestamp) AS truncated_time FROM events; SELECT DATE_TRUNC('minute', event_timestamp) AS truncated_time FROM events;SELECT DATE_TRUNC('second', event_timestamp) AS truncated_time FROM events;

The DATE_TRUNC function truncates a date or timestamp to the specified precision, such as year, month, day, or hour.

Q25

Multiple Choice

Which SQL queries correctly use the TO_CHAR function to format a date in PostgreSQL?

SELECT TO_CHAR(invoice_date, 'YYYY-MM-DD') AS formatted_date FROM invoices; SELECT TO_CHAR(invoice_date, 'MM-DD-YYYY') AS formatted_date FROM invoices; SELECT TO_CHAR(invoice_date, 'DD-MM-YYYY') AS formatted_date FROM invoices;SELECT TO_CHAR(invoice_date, 'YYYY/DD/MM') AS formatted_date FROM invoices;

The TO_CHAR function is used to format a date or timestamp to a specific format, such as 'YYYY-MM-DD'.

Q26

Multiple Choice

Which SQL queries correctly use the DATE_PART function to extract parts of a date in PostgreSQL?

SELECT DATE_PART('year', start_date) AS start_year FROM projects; SELECT DATE_PART('month', start_date) AS start_month FROM projects; SELECT DATE_PART('day', start_date) AS start_day FROM projects;SELECT DATE_PART('hour', start_date) AS start_hour FROM projects;

The DATE_PART function is similar to EXTRACT and is used to get specific parts of a date, such as the year, month, or day.

Q27

Multiple Choice

Which SQL queries correctly use the INTERVAL function to add or subtract time in PostgreSQL?

SELECT start_date + INTERVAL '1 year' AS end_date FROM subscriptions; SELECT start_date + INTERVAL '12 months' AS end_date FROM subscriptions; SELECT start_date + INTERVAL '365 days' AS end_date FROM subscriptions;SELECT start_date + INTERVAL '1 month' AS end_date FROM subscriptions;

The INTERVAL function is used to add or subtract a specific amount of time, such as days, months, or years, to a date or timestamp.

Q28

Multiple Choice

Which SQL queries correctly use the NOW() function to get the current date and time in PostgreSQL?

SELECT * FROM logins WHERE login_time >= NOW() - INTERVAL '1 day'; SELECT * FROM logins WHERE login_time >= NOW() - INTERVAL '24 hours'; SELECT * FROM logins WHERE login_time >= NOW() - INTERVAL '1440 minutes';SELECT * FROM logins WHERE login_time >= NOW() - INTERVAL '1 week';

The NOW() function returns the current date and time. It is commonly used to filter or compare timestamps.

Q29

Multiple Choice

Which SQL queries correctly use the DATE function to cast a timestamp to a date in PostgreSQL?

SELECT DATE(meeting_time) AS meeting_date FROM meetings; SELECT DATE(meeting_time) FROM meetings; SELECT DATE_PART('day', meeting_time) AS meeting_day FROM meetings;SELECT TO_DATE(meeting_time, 'YYYY-MM-DD') AS meeting_date FROM meetings;

The DATE function is used to cast a timestamp or datetime value to a date, removing the time part.

Q30

Multiple Choice

Which SQL queries correctly use the TO_TIMESTAMP function to convert strings to timestamps in PostgreSQL?

SELECT TO_TIMESTAMP(appointment_date, 'YYYY-MM-DD HH:MI:SS') AS appointment_ts FROM appointments; SELECT TO_TIMESTAMP(appointment_date, 'MM-DD-YYYY HH:MI:SS') AS appointment_ts FROM appointments; SELECT TO_TIMESTAMP(appointment_date, 'DD-MM-YYYY HH:MI:SS') AS appointment_ts FROM appointments;SELECT TO_TIMESTAMP(appointment_date, 'YYYY/MM/DD HH:MI:SS') AS appointment_ts FROM appointments;

The TO_TIMESTAMP function converts a string to a timestamp based on the specified format.

PostgreSQL Database Quiz Questions