mysql代表空格的特殊符号

SELECT * FROM users WHERE first_name = 'John ' AND last_name = 'Doe';

UPDATE users SET notes = CONCAT('Name: ', first_name, '\t', last_name) WHERE id = 1;

UPDATE users SET bio = CONCAT('Hello,\nMy name is ', first_name, ' ', last_name) WHERE id = 1;

UPDATE users SET bio = CONCAT('Hello,\rMy name is ', first_name, ' ', last_name) WHERE id = 1;

UPDATE users SET password = CONCAT('p', 'a', 's', 's', 'w', 'o', 'r', 'd', '​') WHERE id = 1;

UPDATE users SET address = CONCAT('123 ', 'Main ', 'St ', 'Apt ', '4B ', ' ') WHERE id = 1;

SELECT * FROM users WHERE REPLACE(first_name, '\t', ' ') = 'John ';

EXPLAIN SELECT * FROM users WHERE first_name = 'John ';