Ingres Database ( ing-GRESS) is a proprietary SQL relational database management system intended to support large commercial and government applications.

Actian Corporation, which announced April 2018 that it is being acquired by HCL Technologies, controls the development of Ingres and makes certified binaries available for download, as well as providing worldwide support. There was an open source release of Ingres but it is no longer available for download from Actian. However, there is a version of the sourcecode still available on GitHub.

In its early years, Ingres was an important milestone in the history of database development. Ingres began as a research project at UC Berkeley, starting in the early 1970s and ending in 1985. During this time Ingres remained largely similar to IBM's seminal System R in concept; it differed in more permissive licensing of source code, in being based largely on DEC machines, both under UNIX and VAX/VMS, and in providing QUEL as a query language instead of SQL. QUEL was considered at the time to run truer to Edgar F. Codd's relational algebra (especially concerning composability), but SQL was easier to parse and less intimidating for those without a formal background in mathematics.

When ANSI preferred SQL over QUEL as part of the 1986 SQL standard (SQL-86), Ingres became less competitive against rival products such as Oracle until future Ingres versions also provided SQL. Many companies spun off of the original Ingres technology, including Actian itself, originally known as Relational Technology Inc., and the NonStop SQL database originally developed by Tandem Computers but now offered by Hewlett Packard Enterprise.