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三十四、MySQL DROP TABLE 删除临时表

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在 MySQSL CREATE TEMPORARY TABLE 创建临时表 中我们学习了 MySQL 临时表的特性和如何创建临时表

临时表只在当前连接可见,当关闭连接时,MySQL 会自动删除表并释放所有空间

但有时候我们可能需要手动删除临时表,比如持久性连接中,我们就要用完即删除

删除临时表和删除普通表的 SQL 语法时一模一样的,都是 DROP TABLE tablename

比如要删除临时表 tbl_language_tmp 则可以使用下面的语句

DROP TABLE tbl_language_tmp;

演示

我们先使用下面的语句创建一个临时表 tbl_language_temp

CREATE TEMPORARY TABLE IF NOT EXISTS `tbl_language_tmp`(
   `id` INT UNSIGNED AUTO_INCREMENT,
   `name` VARCHAR(64) NOT NULL,
   `url` VARCHAR(128) NOT NULL,
   `founded_at` DATE,
   PRIMARY KEY ( `id` )
)ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

运行结果如下

MariaDB [souyunku]> CREATE TEMPORARY TABLE IF NOT EXISTS `tbl_language_tmp`(
->            `id` INT UNSIGNED AUTO_INCREMENT,
->            `name` VARCHAR(64) NOT NULL,
->            `url` VARCHAR(128) NOT NULL,
->            `founded_at` DATE,
->            PRIMARY KEY ( `id` )
->         )ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
Query OK, 0 rows affected (0.01 sec)

可以使用下面的语句往 tbl_language_tmp 中插入数据

INSERT INTO `tbl_language_tmp` (`name`,`url`,`founded_at`) VALUES ('Python','https://tech.souyunku.com','1991-2-20');

运行结果如下

MariaDB [souyunku]> INSERT INTO `tbl_language_tmp` (`name`,`url`,`founded_at`) VALUES ('Python','https://tech.souyunku.com','1991-2-20');
Query OK, 1 row affected (0.00 sec)

可以使用 SELECT * FROM tbl_language_tmp; 查询表中的数据

MariaDB [souyunku]> SELECT * FROM tbl_language_tmp;
+----+--------+---------------------+------------+
| id | name   | url                 | founded_at |
+----+--------+---------------------+------------+
|  1 | Python | https://tech.souyunku.com | 1991-02-20 |
+----+--------+---------------------+------------+
1 row in set (0.00 sec)

然后使用 DROP TABLE tbl_language_tmp;

MariaDB [souyunku]> DROP TABLE tbl_language_tmp;
Query OK, 0 rows affected (0.00 sec)

在使用 SELECT * FROM tbl_language_tmp; 查询表中的数据

MariaDB [souyunku]> SELECT * FROM tbl_language_tmp;
ERROR 1146 (42S02): Table 'souyunku.tbl_language_tmp' doesn't exist

可以看到临时表已经被删除

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