UPPER

UPPER() is a built-in string function in SQL. As the name suggests, it is used to convert all letters in a specified string to uppercase. If the string already consists of all uppercase characters, the function will return the original string.

Syntax for this function is:

UPPER(string)

Here 'string' can be a string value or a column of a table of string(s) type.

Let's assume a table 'students' with column 'name' as below:

name
John Doe
Jane Smith
Kelly Will

If we want all the names in uppercase, we'll use UPPER() function as:

SELECT UPPER(name) as 'Upper Case Name' FROM students;

And we will get:

Upper Case Name
JOHN DOE
JANE SMITH
KELLY WILL

So, UPPER() function helps us to bring an entire string to uppercase for easier comparison and sorting.