Why date handling matters in PostgreSQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select the current date in PostgreSQL.

PostgreSQL

SELECT [1];

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ACURRENT_DATE

BSYSDATE

CGETDATE()

DNOW()

Attempts:

3 left

💡 Hint

Common Mistakes

Using NOW() returns date and time, not just the date.

GETDATE() and SYSDATE are not PostgreSQL functions.

In PostgreSQL, CURRENT_DATE returns the current date without time.

2fill in blank

medium

Complete the code to extract the year from a date column named 'order_date'.

PostgreSQL

SELECT EXTRACT([1] FROM order_date) AS year FROM orders;

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Amonth

Byear

Cday

Dhour

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'month' or 'day' extracts wrong parts of the date.

Using 'hour' extracts time, not date.

The EXTRACT function with year extracts the year part from a date.

3fill in blank

hard

Fix the error in the code to add 7 days to the current date.

PostgreSQL

SELECT CURRENT_DATE + [1];

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A'7 days'

B7

CINTERVAL '7 days'

DDATE '7'

Attempts:

3 left

💡 Hint

Common Mistakes

Adding a plain number to a date causes an error.

Using a string without INTERVAL keyword is invalid.

In PostgreSQL, to add days to a date, you add an INTERVAL value like INTERVAL '7 days'.

4fill in blank

hard

Fill both blanks to convert a text '2024-06-15' to a date and then extract the month.

PostgreSQL

SELECT EXTRACT([1] FROM [2]('2024-06-15')) AS month;

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Amonth

Byear

Cday

D::date

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'year' or 'day' instead of 'month' in EXTRACT.

Not casting the text to date before extracting.

Use EXTRACT(month FROM ...) to get the month, and cast to ::date to convert text to date.

5fill in blank

hard

Fill all three blanks to calculate the difference in days between two dates '2024-06-20' and '2024-06-15'.

PostgreSQL

SELECT ([1]('2024-06-20') - [2]('2024-06-15')) [3] '1 day' AS days_diff;

Drag options to blanks, or click blank then click option'

ADATE

C::interval

D::date

Attempts:

3 left

💡 Hint

Common Mistakes

Not casting strings to dates before subtraction.

Using interval cast incorrectly.

Cast the strings to DATE, subtract them, and cast the result to interval type to get the difference in days.