Isah aims to make the SQL Server code more future proof. Making the SQL code more future proof has the following aspects.
Microsoft declared some syntactic constructions ‘deprecated’. A deprecated construction can still be used in the current version of SQL Server, but it might not in some future version.
Microsoft has pointed out that the SQL Server optimizer expects that the database uses the preferred settings suggested by Microsoft. If you deviate from the preferred settings, query performance can deteriorate.
New SQL Server features that enhance the performance, can only be used if the preferred settings are used as suggested by Microsoft.
Many changes concern the ANSI settings. In this document, the term 'ANSI safe' stands for constructions that do not change behavior when the ANSI settings are changed.
