SELECT REPLACE('Hello, World!', 'Hello', 'Hi');
输出结果为：Hi, World!
UPDATE table_name
SET column_name = REPLACE(column_name, 'old_value', 'new_value');
SELECT REPLACE('1,2,3,4,5', ',', '');
输出结果为：12345
SELECT REPLACE('Hello World', ' ', '_');
输出结果为：Hello_World
