mysql中union不去重复

SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;

SELECT name, age FROM employees
UNION
SELECT name, age FROM contractors;

CREATE TABLE employees (
    id INT PRIMARY KEY,
    name VARCHAR(100),
    age INT
);

CREATE TABLE contractors (
    id INT PRIMARY KEY,
    name VARCHAR(100),
    age INT
);

INSERT INTO employees (id, name, age) VALUES (1, 'Alice', 30);
INSERT INTO employees (id, name, age) VALUES (2, 'Bob', 25);
INSERT INTO contractors (id, name, age) VALUES (1, 'Alice', 30);
INSERT INTO contractors (id, name, age) VALUES (2, 'Charlie', 35);

SELECT name, age FROM employees
UNION
SELECT name, age FROM contractors;

+-------+-----+
| name  | age |
+-------+-----+
| Alice |  30 |
| Bob   |  25 |
| Charlie |  35 |
+-------+-----+