Numeric and decimal precision in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a column with numeric precision of 5 and scale of 2.

PostgreSQL

CREATE TABLE products (price NUMERIC([1]));

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A5, 2

B10, 5

C3, 1

D7, 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one number inside NUMERIC() without scale.

Swapping precision and scale values.

The NUMERIC(5, 2) means the number can have up to 5 digits in total, with 2 digits after the decimal point.

2fill in blank

medium

Complete the code to insert a value with two decimal places into the price column.

PostgreSQL

INSERT INTO products (price) VALUES ([1]);

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A99.99

B123.456

C100

D12.3456

Attempts:

3 left

💡 Hint

Common Mistakes

Inserting values with more than two decimal places.

Inserting integer values without decimal places.

Since the price column has scale 2, values must have at most two digits after the decimal point.

3fill in blank

hard

Fix the error in the SELECT statement to round the price to 1 decimal place.

PostgreSQL

SELECT ROUND(price, [1]) FROM products;

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A3

B0

C-1

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 rounds to whole number, not one decimal place.

Using negative numbers rounds to tens or hundreds.

ROUND(price, 1) rounds the price to one decimal place.

4fill in blank

hard

Fill both blanks to create a table with a decimal column and insert a value with correct precision.

PostgreSQL

CREATE TABLE sales (amount DECIMAL([1], [2]));
INSERT INTO sales (amount) VALUES (123.45);

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A6

B2

C4

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using scale larger than precision.

Choosing precision smaller than number of digits in value.

DECIMAL(6, 2) means 6 total digits with 2 after the decimal point, so 123.45 fits.

5fill in blank

hard

Fill all three blanks to select prices rounded to 0 decimal places and filter prices greater than 100.

PostgreSQL

SELECT ROUND(price, [1]) AS rounded_price FROM products WHERE price [2] [3];

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A1

B>

C100

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 0 for rounding decimal places.

Using wrong comparison operator in WHERE clause.

ROUND(price, 0) rounds to whole numbers. The WHERE clause filters prices greater than 100.