mysqlに接続

***********@mbp ***** % mysql -u root
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 10
Server version: 8.0.28 Homebrew

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Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

データベース（スキーマ）の一覧を表示

mysql> show databases
    -> ;
+---------------------------+
| Database                  |
+---------------------------+
| ******_development        |
| ******_review_development |
| ******_review_test        |
| ******_test               |
| information_schema        |
| mysql                     |
| performance_schema        |
| sys                       |
| training                  |
+---------------------------+
9 rows in set (0.00 sec)

******_developmentのデータベースを表示させる

失敗

mysql> show ******_development
    -> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'garden_development' at line 1

成功

mysql> show tables from ******_development;
+------------------------------+
| Tables_in_******_development |
+------------------------------+
| a                            |
| h                            |
| l                            |
| p                            |
| p                            |
| s                            |
| u                            |
| v                            |
+------------------------------+
8 rows in set (0.00 sec)

データベースの中のテーブルのカラムの情報を表示させる。

mysql> SHOW COLUMNS FROM ******* FROM ******_development;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id    | tinyint     | NO   | PRI | NULL    |       |
| name  | varchar(50) | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

テーブルの抽出をする

失敗

mysql> select * from *********;
ERROR 1046 (3D000): No database selected

成功　useでデータベースを対象にしてから抽出作業に移る

mysql> use ******_development;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select * from *******;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | a            |
|  2 | b            |
|  3 | c            |
|  4 | d            |
+----+--------------+
4 rows in set (0.01 sec)

感想

当たり前のことだけど忘れていた。
また同じ内容の記事をあげそうだ。