There is a very close relationship between database tablespaces and datafiles

Technically --> A database is linked with one or more tablespaces

and a tablespace is linked with one or more datafile

One datafile has not linked with two or more tablespaces means one datafile is linked with only one tablespace and this is the same case in relation of database and tablespace -- > one tablespace is not linked with one or more databases but a database has one or more tablespaces

Thanks

Database : Collection of data is called database.

Tablespace : An Oracle Database consists of one or more logical storage units called tablespace which collectively use to store all the database's data.

DataFile : Each tablespace in an Oracle Database consists of one or more datafiles which are used to store data physically.

Schema : A schema is a named collection of objects that include Tables Triggers constraints Indexes Views etc. A user can only be associated with one schema and that is the same name as the user's. Username and schema are often used interchangeably.

A database consists of one or many tablespaces. A database has one-to-many relationship with tablespaces. That is one database can have many tablespaces but a given tablespace can belong to only one database. Similary a tablespace has one-to-many relationship with datafiles. That is a tablespace can have one or many datafiles but a given datafile can belong to only one tablespace.

Here is an example:

select * from v$database;
This will give you the name of the database dbid created log_mode etc. You will see only one row.

select *
from v$tablespace;
This will give TS# tablespace_name etc. You will see many rows. TS# is primary key here.

select *
from v$datafile;
This will give you the datafiles name TS# where TS# here is a foreign key referencing the TS# of the v$tablespace table. Also you can see name column where the complete path is available as
/u5/fdgre2/fergdb/horm_data_01.dbf
/u5/fdgre2/fergdb/horm_data_02.dbf ...... etc.


So the short and correct answer is:

A database has one-to-many relationship with tablespace.
A tablesapce has one-to-many relationship with datafile.

Ram Srinivasan

Table Space : The table space is useful for storing the data in the
database. When a database is created two table spaces are created.



a) System Table Space : This data file stores
all the tables related to the system and dba tables

b) User Table Space : This data file stores all the
user related tables. We should have separate table spaces for storing the tables
and indexes so that the access is fast.



Data Files : Every Oracle Data Base has one or more physical data files.
They store the data for the database. Every data-file is associated with only
one database. Once the Data file is created the size cannot change. To increase
the size of the database to store more data we have to add data file.