UPPER and LOWER functions in SQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the UPPER function do in SQL?

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

beginner

What is the purpose of the LOWER function in SQL?

The LOWER function converts all letters in a text string to lowercase letters.

beginner

Write a SQL query to convert the column 'name' to uppercase.

SELECT UPPER(name) FROM table_name;

intermediate

How can you make a case-insensitive search using UPPER or LOWER?

Convert both the column and the search term to the same case using UPPER or LOWER, then compare them.

beginner

If you apply LOWER to 'Hello World!', what is the result?

The result is 'hello world!'. Only letters change case; punctuation and spaces stay the same.

What will SELECT UPPER('sql') return?

A 'SQL'

B 'sql'

C 'Sql'

D 'sQl'

UPPER converts all letters to uppercase, so 'sql' becomes 'SQL'.

Which function converts text to lowercase in SQL?

A LOWER()

B UPPER()

C LOWCASE()

D DOWN()

LOWER() is the standard SQL function to convert text to lowercase.

How can you compare two strings ignoring case differences?

A Compare strings directly without functions

B Use UPPER on both strings before comparing

C Use UPPER on one string only

D Use LOWER on one string only

Converting both strings to the same case (UPPER or LOWER) ensures case-insensitive comparison.

What happens to numbers and punctuation when using UPPER or LOWER?

A They change to uppercase or lowercase

B They are removed

C They stay the same

D They cause an error

Numbers and punctuation are not affected by UPPER or LOWER functions.

Which SQL function would you use to make 'Hello' into 'hello'?

A UPPER('Hello')

B CAPITALIZE('Hello')

C LOWCASE('Hello')

D LOWER('Hello')

LOWER('Hello') converts all letters to lowercase, resulting in 'hello'.

Explain how UPPER and LOWER functions work in SQL and give an example of each.

Think about changing letter cases in text columns.

Describe a real-life situation where using UPPER or LOWER in SQL would be helpful.

Imagine searching names or emails without worrying about letter case.