Syntax:
DROP [UNDO] TABLESPACE tablespace_name
    [ENGINE [=] engine_name]

This statement drops a tablespace that was previously created using
CREATE TABLESPACE. It is supported by the NDB and InnoDB storage
engines.

The UNDO keyword, introduced in MySQL 8.0.14, must be specified to drop
an undo tablespace. Only undo tablespaces created using CREATE UNDO
TABLESPACE syntax can be dropped. An undo tablespace must be in an
empty state before it can be dropped. For more information, see
https://dev.mysql.com/doc/refman/8.0/en/innodb-undo-tablespaces.html.

ENGINE sets the storage engine that uses the tablespace, where
engine_name is the name of the storage engine. Currently, the values
InnoDB and NDB are supported. If not set, the value of
default_storage_engine is used. If it is not the same as the storage
engine used to create the tablespace, the DROP TABLESPACE statement
fails.

tablespace_name is a case-sensitive identifier in MySQL.

For an InnoDB general tablespace, all tables must be dropped from the
tablespace prior to a DROP TABLESPACE operation. If the tablespace is
not empty, DROP TABLESPACE returns an error.

An NDB tablespace to be dropped must not contain any data files; in
other words, before you can drop an NDB tablespace, you must first drop
each of its data files using ALTER TABLESPACE ... DROP DATAFILE.

Notes

o A general InnoDB tablespace is not deleted automatically when the
  last table in the tablespace is dropped. The tablespace must be
  dropped explicitly using DROP TABLESPACE tablespace_name.

o A DROP DATABASE operation can drop tables that belong to a general
  tablespace but it cannot drop the tablespace, even if the operation
  drops all tables that belong to the tablespace. The tablespace must
  be dropped explicitly using DROP TABLESPACE tablespace_name.

o Similar to the system tablespace, truncating or dropping tables
  stored in a general tablespace creates free space internally in the
  general tablespace .ibd data file which can only be used for new
  InnoDB data. Space is not released back to the operating system as it
  is for file-per-table tablespaces.

InnoDB Examples

This example demonstrates how to drop an InnoDB general tablespace. The
general tablespace ts1 is created with a single table. Before dropping
the tablespace, the table must be dropped.

mysql> CREATE TABLESPACE `ts1` ADD DATAFILE 'ts1.ibd' Engine=InnoDB;     

mysql> CREATE TABLE t1 (c1 INT PRIMARY KEY) TABLESPACE ts1 Engine=InnoDB;     

mysql> DROP TABLE t1;

mysql> DROP TABLESPACE ts1;

This example demonstrates dropping an undo tablespace. An undo
tablespace must be in an empty state before it can be dropped. For more
information, see
https://dev.mysql.com/doc/refman/8.0/en/innodb-undo-tablespaces.html.

mysql> DROP UNDO TABLESPACE undo_003;

NDB Example

This example shows how to drop an NDB tablespace myts having a data
file named mydata-1.dat after first creating the tablespace, and
assumes the existence of a log file group named mylg (see [HELP CREATE
LOGFILE GROUP]).

mysql> CREATE TABLESPACE myts
    ->     ADD DATAFILE 'mydata-1.dat'
    ->     USE LOGFILE GROUP mylg
    ->     ENGINE=NDB;

You must remove all data files from the tablespace using ALTER
TABLESPACE, as shown here, before it can be dropped:

mysql> ALTER TABLESPACE myts
    ->     DROP DATAFILE 'mydata-1.dat'
    ->     ENGINE=NDB;

mysql> DROP TABLESPACE myts;

URL: https://dev.mysql.com/doc/refman/8.0/en/drop-tablespace.html

