الضم: || وCONCAT

SELECT first_name || ' ' || last_name AS full_name FROM users;
SELECT 'Hello, ' || name || '!' FROM users;

SELECT first_name || ' ' || NULL;     -- NULL

-- Defend with COALESCE:
SELECT first_name || ' ' || COALESCE(last_name, '') FROM users;

SELECT CONCAT(first_name, ' ', last_name) FROM users;
SELECT CONCAT(first_name, ' ', NULL);     -- 'first_name ' (no NULL)

SELECT CONCAT_WS(' ', title, first_name, middle_initial, last_name) AS pretty_name
FROM users;
-- ' ' between non-NULL fields only

SELECT 'Order #' || id::TEXT  FROM orders;
SELECT CONCAT('Order #', id) FROM orders;     -- CONCAT auto-casts

SELECT id,
       email,
       CONCAT_WS(', ', city, region, country) AS location
FROM users;

SELECT user_id,
       STRING_AGG(name, ', ' ORDER BY name) AS tag_names
FROM user_tags
GROUP BY user_id;

SELECT format('User %s (id=%s) joined on %s',
              full_name, id, created_at::DATE)
FROM users;

INSERT INTO contacts (phone) VALUES (NULLIF(:phone, ''));

SELECT $$Hello,
'World' — with quotes!$$;

SELECT $custom_tag$ ... $custom_tag$;