In a database system the phrase `query' subsumes all actions manipulating the DB (i.e. any method or function like adding, deleting, searching, etc.).
The most common language to send queries to a relational database as defined by Codd (see 6.1.3) is the Standard Query Language (SQL) described in the ISO/IEC 9075:1992 Norm. This standard is implemented in nearly every relational database application today.