Butler SQL is a now-defunct SQL-based database server for the "classic" Mac OS from EveryWare Development. For much of its history it was partnered with another EveryWare product, Tango, that built dynamic database pages from SQL data. The product eventually ended up with Pervasive Software, although it is no longer sold.
Butler was introduced to take advantage of new a Mac OS component known as the Data Access Manager (DAM), which was similar in concept to ODBC, allowing end-user client programs to access various data sources. Butler itself used another Apple technology, Data Access Language (DAL), which was a variant of SQL that included additional flow-control and data manipulation instructions. Butler spoke DAL as its native internal language, and supplied a number of DAM extensions to provide connectivity over a variety of networking systems. Butler 2.0, released in May 1996, added direct ODBC links as well.
Butler suffered from performance problems due to the single-user nature of the Mac OS. In particular, file access was single-threaded and multitasking was coordinated by the applications, not the operating system.