Mathematical functions (ROUND, CEIL, FLOOR, ABS) in PostgreSQL - Cheat Sheet & Quick Revision

Recall & Review

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What does the ROUND function do in PostgreSQL?

The ROUND function rounds a numeric value to the nearest whole number or to a specified number of decimal places.

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How does the CEIL function behave in PostgreSQL?

The CEIL (ceiling) function returns the smallest integer greater than or equal to the given number.

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Explain the FLOOR function in PostgreSQL.

The FLOOR function returns the largest integer less than or equal to the given number.

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What is the purpose of the ABS function in PostgreSQL?

The ABS function returns the absolute value of a number, which means it removes any negative sign and returns a positive number or zero.

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Which function would you use to round 3.14159 to 2 decimal places in PostgreSQL?

You would use ROUND(3.14159, 2) which returns 3.14.

What does CEIL(4.3) return in PostgreSQL?

A 5

B 3

C 4.3

D 4

CEIL returns the smallest integer greater than or equal to the number, so CEIL(4.3) is 5.

Which function returns the largest integer less than or equal to a number?

A ROUND

B CEIL

C ABS

D FLOOR

FLOOR returns the largest integer less than or equal to the input number.

What is the result of ABS(-7) in PostgreSQL?

A 7

B -7

C 0

D -1

ABS returns the positive value of the number, so ABS(-7) is 7.

How does ROUND(5.678, 1) evaluate?

A 6

B 5.6

C 5.7

D 5

ROUND rounds to the specified decimal place, so 5.678 rounded to 1 decimal place is 5.7.

Which function would you use to get the integer part of 9.99 by rounding down?

A ROUND

B FLOOR

C CEIL

D ABS

FLOOR rounds down to the nearest integer, so FLOOR(9.99) returns 9.

Describe the difference between CEIL and FLOOR functions in PostgreSQL.

Think about rounding numbers up or down.

Explain how you would use the ROUND function to round a number to 3 decimal places.

ROUND(number, decimal_places)