In computing, the Oracle Call Interface consists of a set of C-language software APIs which provide an interface to the Oracle database.
OCI offers a procedural API for not only performing certain database administration tasks , but also for using PL/SQL or SQL to query, access, and manipulate data. The OCI library, based on Oracle's undocumented User Programmatic Interface , acts as an "interpreter" between applications and the low-level database network protocol.