Ingres uses the Ingres Structured Query Language (SQL) to manipulate data. SQL consists of high‑level descriptions of actions to be performed against data, such as select and prepare. SQL requires no instructions for accessing data; it navigates its own way through the database.

The gateways use OpenSQL, which is a subset of Ingres SQL. OpenSQL is highly portable because it is designed to open applications to many different types of databases. All Ingres products support OpenSQL.

OpenSQL works with both Ingres and non‑Ingres databases. Therefore, applications coded in OpenSQL are more portable than applications that use the full Ingres SQL extensions. Applications written in SQL must be rewritten in OpenSQL for use with the gateways.

For more information about using OpenSQL, see the Ingres OpenSQL Reference Guide and the appendixes for the specific host DBMSs.

Although Enterprise Access follows the OpenSQL standard, there are instances where the Enterprise Access behavior differs from Ingres. For additional information, see Developing Portable Applications.