Why PostgreSQL string functions are powerful - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to convert the string 'hello' to uppercase using a PostgreSQL function.

PostgreSQL

SELECT [1]('hello');

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ATRIM

BLOWER

CINITCAP

DUPPER

Attempts:

3 left

💡 Hint

Common Mistakes

Using LOWER instead of UPPER.

Using TRIM which removes spaces, not changes case.

The UPPER function converts all letters in a string to uppercase.

2fill in blank

medium

Complete the code to find the position of the substring 'cat' in the string 'concatenate'.

PostgreSQL

SELECT POSITION([1] IN 'concatenate');

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A'cat'

B'rat'

C'bat'

D'dog'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a substring that does not exist in the string.

Forgetting to put the substring in quotes.

The POSITION function returns the starting position of the substring 'cat' in the string.

3fill in blank

hard

Fix the error in the code to extract the first 4 characters from the string 'PostgreSQL'.

PostgreSQL

SELECT SUBSTRING('PostgreSQL' [1] 4);

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ASTART 1 LENGTH

BFOR 4 FROM 1

CFROM 1 FOR

DFROM 4 FOR

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of FOR and FROM.

Using incorrect keywords like START or LENGTH.

The correct syntax for SUBSTRING is SUBSTRING(string FROM start FOR length).

4fill in blank

hard

Fill both blanks to trim spaces from both ends of the string and convert it to lowercase.

PostgreSQL

SELECT [1]([2]('  Hello World  '));

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ALOWER

BUPPER

CTRIM

DINITCAP

Attempts:

3 left

💡 Hint

Common Mistakes

Using UPPER instead of LOWER for case conversion.

Not trimming spaces before changing case.

First, TRIM removes spaces from both ends. Then, LOWER converts the string to lowercase.

5fill in blank

hard

Fill all three blanks to create a query that replaces 'day' with 'night' in the string, converts it to uppercase, and trims spaces.

PostgreSQL

SELECT [1]([2](REPLACE('Good day  ', [3], 'night')));

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ATRIM

BUPPER

C'day'

DREPLACE

Attempts:

3 left

💡 Hint

Common Mistakes

Putting TRIM inside REPLACE incorrectly.

Not quoting the substring 'day'.

Changing case before replacing.

The REPLACE function swaps 'day' with 'night'. Then UPPER converts to uppercase. Finally, TRIM removes spaces.

Note: The code applies REPLACE first, then UPPER, then TRIM.