两个字符的字段相加mysql

CREATE TABLE users (
    id INT PRIMARY KEY,
    first_name VARCHAR(50),
    last_name VARCHAR(50)
);

SELECT CONCAT(first_name, ' ', last_name) AS full_name FROM users;

SELECT CONCAT(first_name, ' ', last_name) AS full_name FROM users;

SELECT CONCAT('Hello, ', first_name, ' ', last_name, '!') AS greeting FROM users;

SELECT CONCAT(COALESCE(first_name, ''), ' ', COALESCE(last_name, '')) AS full_name FROM users;

SELECT GROUP_CONCAT(CONCAT(first_name, ' ', last_name) SEPARATOR ', ') AS full_names FROM users;