Table creation
CREATE TABLE `users` (
`id` INT UNSIGNED NOT NULL,
`name` VARCHAR(100) NOT NULL,
PRIMARY KEY(`id`)
);
CREATE TABLE `email_address` (
`id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`user_id` INT UNSIGNED NOT NULL,
`email_address` VARCHAR(50) NOT NULL,
INDEX pn_user_index(`user_id`),
FOREIGN KEY (`user_id`) REFERENCES users(`id`) ON DELETE CASCADE,
PRIMARY KEY(`id`)
);
Data insertion
INSERT INTO users (id, name) VALUES (1, 'Mark'), (2, 'Tom'), (3, 'Robin');
INSERT INTO email_address (user_id, email_address) VALUES
(1, '[email protected]'), (1, '[email protected]'), (1, '[email protected]'),
(2, '[email protected]'), (2, '[email protected]'), (2, '[email protected]'),
(3, '[email protected]'), (3, '[email protected]'), (3, '[email protected]');
SQL query
SELECT usr.name AS name
, (SELECT email.email_address
FROM email_address AS email
WHERE email.user_id = usr.id) AS email
FROM users AS usr;
With the use of above my MySQL query, how can I avoid the MySQL Error 'Subquery returns more than 1 row' and select the all the relevant email address for particular User as below. Thanks.
+----------+-------------------------------------------------+
| name | email |
+----------+-------------------------------------------------+
| Mark | [email protected], [email protected], [email protected] |
| Tom | [email protected], [email protected], [email protected] |
| Robin | [email protected], [email protected], [email protected] |
+----------+----------+--------------------------------------+
GROUP_CONCAT
with SEPARATOR
and simplify your query a bit:
SELECT users.name AS name,
(SELECT GROUP_CONCAT(email_address.email_address SEPARATOR ', ')
FROM email_address
WHERE email_address.user_id = users.id) AS email
FROM users
Reference: https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html#function_group-concat