A '''database abstraction layer''' ('''DBAL'''<ref>{{cite book|first1=Tim|last1=Ambler|first2=Nicholas|last2=Cloud|title=JavaScript Frameworks for Modern Web Dev|url=https://books.google.com/books?id=2IfDCgAAQBAJ&pg=PA346|year=2015|publisher=Apress|isbn=978-1-4842-0662-1|page=346}}</ref> or '''DAL''') is an [[application programming interface]] which unifies the communication between a computer application and [[database]]s such as [[MSSQL|SQL Server]], [[IBM DB2|DB2Db2]], [[MySQL]], [[PostgreSQL]], [[Oracle database|Oracle]] or [[SQLite]]. Traditionally, all database vendors provide their own interface that is tailored to their products. It is up to the application programmer to implement code for the database interfaces that will be supported by the application. Database abstraction layers reduce the amount of work by providing a consistent API to the developer and hide the database specifics behind this interface as much as possible. There exist many abstraction layers with different interfaces in numerous programming languages. If an application has such a layer built in, it is called '''database-agnostic'''.<ref>{{cite web |url=http://searchdatamanagement.techtarget.com/definition/database-agnostic |title = What is database-agnostic? - Definition from WhatIs.com}}</ref>
