From a compiler as system environment perspective, there are a couple of approaches used:

  -- 4gl languages[0] aka direct in-language support for database(s)

  -- programming language library extensions for dealing with specific types of databases/database formats

  -- use of a programming language's standard file/internet read/write functions to import/export formats such as ODBC,json, html and ascii delimited file(s).

Description of types of DBMS[0], in-memory DBMS[1][2]

List of in-memory databases[3]

A DBMS not designed as an in-memory DBMS can realize in-memory DBMS benefits via being used on a ramdrive[4].

[0] : https://www.techbaz.org/blogs/dbms.php

[1] : https://en.wikipedia.org/wiki/In-memory_database

[2] : https://medium.com/@denisanikin/what-an-in-memory-database-i...

[3] : https://en.wikipedia.org/wiki/List_of_in-memory_databases

[4] : https://en.wikipedia.org/wiki/RAM_drive (* virtual environment : https://snarky.ca/how-virtual-environments-work/

    vs getting around physical board space limitations :

    ddr ram over pcie : https://ddramdisk.store/shop/

    clx, omi : https://semiengineering.com/cxl-and-omi-competing-or-complementary/

 
)

** Generally, the system environment a program is started from provides the

interface to persistent/non-persistent resources used by/accessible to the

running program. Within a program, the resources provided by system environment

running the program can be interpreted/used by the running program in a way

different from the system environment.

-- The running program does not have to interpret the persistent/non-persistent

resources in the same manner as the OS. aka data file program provided by OS is

stored in windows file format on hard drive. The program can interpret the

aforementioned data in the file as something other than a windows format after

the OS has fetched the file information.

** Not clear what single category of system environment using. (OS, DB,

integrated developer environment, file editor, compiled program,

interpreted program).

** Not clear if talking about program data input sources & when/how input

sources are used. aka From command line, redirecting database query result

containing a runnable shell script as input to a command line shell.

** The system environment a program is run from can make the resources

a running program uses appear to come from something different than

where the system environment got the resources from -- aka. program

environment provides running program a file from local hard disk,

where the 'file from local hard disk' might have been fetched by the system

environment via internet connection from a cd located on a remote machine.

Virtual machines running macOS under windows is one example.