DevOps, CI/CD and Automation

Hi everyone!
I need to convert a values fetched from a db table in a unix timestamp (seconds passed by january first 1970).

The table is like this
create table test(.... ts timestamp not null...);

and the code to define the output variable (for a select statement) is the following, where time is an OCIDateTime variable

OCIDefineByPos(stmth, &defineh, errh, pos, (dvoid *) time, 0, SQLT_ODT,
(dvoid *) 0, (ub2 *) 0, (ub2 *) 0, OCI_DEFAULT);

once I have initialized "time", how can I convert his content to unix timestamp?
And viceversa, how can I put an int value rapresenting a unix timestamp in an OCIDateTime variable, and then insert it correctly inside mt table?
thank you!
GePs