20170627 Architect's Diary - Tablespace

How can I know which tablespace is MY default tablespace?

select * from DBA_USERS where USERNAME='MyADP';`

Note: Not all users can do this. If your user does not have access to DBA_USERS, you may get

ORA-00942: table or view does not exist
00942. 00000 -  "table or view does not exist"
*Cause:
*Action:
Error at Line: 48 Column: 15

Where is this specified?

When you create a new user, you can optionally specify the default tablespace and default temporary tablespace for any objects created by that user. For example

CREATE USER phil IDENTIFIED BY s3cr3t
      DEFAULT TABLESPACE philtablespace
      TEMPORARY TABLESPACE philtemp;

If you omit the clauses when creating the user, the user will inherit the database default values. These can be queried as follows:

SELECT *
  FROM DATABASE_PROPERTIES
  WHERE PROPERTY_NAME LIKE `DEFAULT%TABLESPACE`

You would then get something like:

PROPERTY_NAME                 PROPERTY_VALUE    DESCRIPTION
DEFAULT_PERMANENT_TABLESPACE	SYSTEM	          Default Permanent Tablespace ID
DEFAULT_TEMP_TABLESPACE	      TEMP	            ID of default temporary tablespace

More information see here on stackexchange.