lower(str)The lower function converts its argument to a string and then converts all upper case letters in the string to lower case.
Example:
lower(str) in { 'yes', 'no' }
upper(str)The upper function converts its argument to a string and then converts all lower case letters in the string to upper case.
Example (to capitalize a name):
@ { upper(substr(name, 0, 1)), substr(name, 1) }