UPPER, LOWER, INITCAP in PostgreSQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this UPPER function?

Given the following SQL query, what will be the output?

PostgreSQL

SELECT UPPER('Hello World!') AS result;

A hello world!

B HELLO WORLD!

C Hello World!

D hELLO wORLD!

💡 Hint

UPPER converts all letters to uppercase.

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

❓ query_result

intermediate

What does LOWER do to mixed case text?

What is the output of this query?

PostgreSQL

SELECT LOWER('PostgreSQL Is Fun!') AS result;

A postgresql is fun!

B pOSTGRESql iS fUN!

C POSTGRESQL IS FUN!

D PostgreSQL Is Fun!

💡 Hint

LOWER converts all letters to lowercase.

The LOWER function converts all letters in the string to lowercase letters.

❓ query_result

advanced

How does INITCAP format this sentence?

What will be the output of this query?

PostgreSQL

SELECT INITCAP('welcome to the world of SQL') AS result;

A Welcome To The World Of Sql

B WELCOME TO THE WORLD OF SQL

C welcome to the world of sql

D Welcome to the world of SQL

💡 Hint

INITCAP capitalizes the first letter of each word.

The INITCAP function capitalizes the first letter of each word and makes the rest lowercase.

🧠 Conceptual

advanced

Which function would you use to make a case-insensitive search?

You want to find all rows where the column name matches 'alice' regardless of case. Which function is best to use in the WHERE clause?

A WHERE INITCAP(name) = 'Alice'

B WHERE LOWER(name) = 'ALICE'

C WHERE UPPER(name) = 'ALICE'

D WHERE name = 'alice'

💡 Hint

Think about converting both sides to the same case.

Using UPPER(name) = 'ALICE' converts the column to uppercase and compares it to uppercase 'ALICE', making the search case-insensitive.

📝 Syntax

expert

What error does this query raise?

Consider this query: SELECT INITCAP(12345) AS result; What error will PostgreSQL raise?

A ERROR: syntax error at or near "12345"

B ERROR: invalid input syntax for type integer

C No error, returns '12345'

D ERROR: function initcap(integer) does not exist

💡 Hint

INITCAP expects a string input, not a number.

The INITCAP function requires a string argument. Passing an integer causes PostgreSQL to report that the function with integer argument does not exist.