String Functions

String functions transform text values — UPPER()/LOWER() change case, TRIM() strips whitespace, SUBSTRING() pulls out part of a string.

Source data — Pattern 3: Built-in Functions

All queries run against the shared employees table (see schema.sql). This pattern needs two columns not used before: hire_date (topic 17) and bonus, nullable (topics 19–20).

String Functions — source table 1

What it does

String functions transform text values — UPPER()/LOWER() change case, TRIM() strips whitespace, SUBSTRING() pulls out part of a string. They're applied per-row in the SELECT list and don't change the stored data, only the output.

Problem

Convert all employee names to uppercase.

SELECT UPPER(first_name) AS first_name_upper,
       UPPER(last_name)  AS last_name_upper
FROM employees;

Result

String Functions — result 2