MySQL の INSERT SELECT

INSERT INTO TARGET_TABLE (COLUMN_LIST)
SELECT SOURCE_COLUMNS FROM SOURCE_TABLE;

INSERT INTO rating_count (rating, films)
SELECT rating, COUNT(*) FROM sakila.film GROUP BY rating;

Query OK, 5 rows affected (0.00 sec)
Records: 5  Duplicates: 0  Warnings: 0

SELECT * FROM rating_count ORDER BY films DESC;

+--------+-------+
| rating | films |
+--------+-------+
| PG-13  |   223 |
| NC-17  |   210 |
| R      |   195 |
| PG     |   194 |
| G      |   178 |
+--------+-------+
5 rows in set (0.00 sec)

INSERT INTO member (first_name, last_name, email, joined)
SELECT first_name, last_name, CONCAT(LOWER(first_name), '.', LOWER(last_name), '@example.net'), '2026-05-01'
FROM sakila.staff;

Query OK, 2 rows affected (0.01 sec)
Records: 2  Duplicates: 0  Warnings: 0

SELECT member_id, first_name, last_name, email FROM member WHERE joined = '2026-05-01';

+-----------+------------+-----------+--------------------------+
| member_id | first_name | last_name | email                    |
+-----------+------------+-----------+--------------------------+
|         4 | Mike       | Hillyer   | mike.hillyer@example.net |
|         5 | Jon        | Stephens  | jon.stephens@example.net |
+-----------+------------+-----------+--------------------------+
2 rows in set (0.00 sec)

INSERT INTO rating_count (rating, films)
SELECT rating FROM sakila.film GROUP BY rating;

ERROR 1136 (21S01): Column count doesn't match value count at row 1

INSERT INTO rating_count (rating, films)
SELECT rating, COUNT(*) FROM sakila.film WHERE rating = 'G' GROUP BY rating;

ERROR 1062 (23000): Duplicate entry 'G' for key 'rating_count.PRIMARY'