mysql查询中的Concat ()函数或替代解决方案

CONCAT(string1, string2, ..., stringN)

SELECT CONCAT('Hello', ' ', 'World') AS result;

result
-------
Hello World

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

INSERT INTO users (id, first_name, last_name) VALUES (1, 'John', 'Doe');
INSERT INTO users (id, first_name, last_name) VALUES (2, 'Jane', 'Smith');

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

full_name
----------------
John Doe
Jane Smith

SELECT first_name || ' ' || last_name AS full_name FROM users;

CONCAT_WS(separator, string1, string2, ..., stringN)

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

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

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