Data Access Language: Difference between revisions

Revision as of 13:44, 21 May 2005

Revision as of 13:44, 21 May 2005

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'''Data Access Language''', or more commonly simply '''DAL''', was a [[SQL]]-like language parser released by [[Apple]] in the early 1990s to provide unified [[client/server]] access to [[database management system]]s. Apple purchased the system from a small vendor, who called it '''CL/1''' (''command language 1'') prior to the purchase.

DAL was essentially a cut-down version of SQL, supporting only the most basic functionality, but adding clean syntax for cursor operations, logic, and loops. When sent a command the DAL interpreter broke down the statement and re-built it into subqueries for the underlying data sources. For instance, DAL users could write a single SQL query that would be applied to two physically separate databases, DAL would then produce smaller subqueries for each server, and combine the results on the way back. This is similar in nature to how [[Microsoft Access]] works, but provided at a system-wide level. In this respect DAL is much higher level in concept than systems like [[ODBC]] or [[JDBC]], which essentially define the "pipe" to the data source and little more.