MySQLまたはMariaDBのデータベース内のテーブル数を確認する方法をお伝えします。
サンプルデータベースを次のように準備します。
-- データベース作成
CREATE DATABASE sample_database;
(out)
-- データベース指定
use sample_database;
(out)
-- テーブル作成
CREATE TABLE sample01 (col11 INT, col12 CHAR(10));
CREATE TABLE sample02 (col21 INT, col22 CHAR(10), col23 DOUBLE);
データベース内のテーブルに関する情報はinformation_schema.tablesにあります。
SHOW FULL COLUMNS FROM information_schema.tables;
(out)
(out)+-----------------+---------------------+-----------------+------+-----+---------+-------+------------+---------+
(out)| Field | Type | Collation | Null | Key | Default | Extra | Privileges | Comment |
(out)+-----------------+---------------------+-----------------+------+-----+---------+-------+------------+---------+
(out)| TABLE_CATALOG | varchar(512) | utf8_general_ci | NO | | | | select | |
(out)| TABLE_SCHEMA | varchar(64) | utf8_general_ci | NO | | | | select | |
(out)| TABLE_NAME | varchar(64) | utf8_general_ci | NO | | | | select | |
(out)| TABLE_TYPE | varchar(64) | utf8_general_ci | NO | | | | select | |
(out)| ENGINE | varchar(64) | utf8_general_ci | YES | | NULL | | select | |
(out)| VERSION | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| ROW_FORMAT | varchar(10) | utf8_general_ci | YES | | NULL | | select | |
(out)| TABLE_ROWS | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| AVG_ROW_LENGTH | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| DATA_LENGTH | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| MAX_DATA_LENGTH | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| INDEX_LENGTH | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| DATA_FREE | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| AUTO_INCREMENT | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| CREATE_TIME | datetime | NULL | YES | | NULL | | select | |
(out)| UPDATE_TIME | datetime | NULL | YES | | NULL | | select | |
(out)| CHECK_TIME | datetime | NULL | YES | | NULL | | select | |
(out)| TABLE_COLLATION | varchar(32) | utf8_general_ci | YES | | NULL | | select | |
(out)| CHECKSUM | bigint(21) unsigned | NULL | YES | | NULL | | select | |
(out)| CREATE_OPTIONS | varchar(2048) | utf8_general_ci | YES | | NULL | | select | |
(out)| TABLE_COMMENT | varchar(2048) | utf8_general_ci | NO | | | | select | |
(out)+-----------------+---------------------+-----------------+------+-----+---------+-------+------------+---------+
そのinformation_schema.tablesを用いて、sample_databaseデータベース内のテーブル数を確認するSQLコードは次になります。
SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = 'sample_database';
(out)
(out)+----------+
(out)| COUNT(*) |
(out)+----------+
(out)| 2 |
(out)+----------+
(out)1 row in set (0.00 sec)
MySQL データベース内のテーブル数を確認する方法
