8. LOWER, UPPER, SUBSTRING.sql

-- SUBSTRING

-- (SYNTAX)
-- SUBSTRING(attribute, start_position, length)

--  is used to extract a substring from a larger string. 

select SUBSTRING(CITY, 1, 1) from STATION;
-- extracts the first character of the CITY column.

select SUBSTRING(CITY, -1, 1) from STATION;
-- extracts the last character of the CITY column.

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-- LOWER

-- (SYNTAX)
-- LOWER(attribute)

-- a string function in SQL that is used to convert a string to lowercase.

select LOWER(CITY) from STATION.

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-- UPPER

-- (SYNTAX)
-- UPPER(attribute)

-- a string function in SQL that is used to convert a string to uppercase.

select UPPER(CITY) from STATION.