Postgres 11

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CREATE TABLE customers(first_name VARCHAR(10), last_name VARCHAR(10));

INSERT INTO customers(first_name, last_name) VALUES ('Lukas', 'Eder'),('X','Y')

CREATE TABLE

INSERT 0 2

SELECT   first_name || ' ' || last_name
FROM     customers
WHERE    first_name || ' ' || last_name LIKE 'L% E%'
GROUP BY first_name || ' ' || last_name
ORDER BY first_name || ' ' || last_name

?column?

Lukas Eder

SELECT 1

SELECT s.full_name
FROM customers c
, LATERAL (VALUES(c.first_name || ' ' || c.last_name)) s(full_name)
WHERE s.full_name LIKE 'L% E%'
GROUP BY s.full_name
ORDER BY s.full_name

full_name

Lukas Eder

SELECT 1