Creating and executing user-defined functions

User-defined functions (UDFs) return a single value to the calling environment.

You can install Sybase IQ in a wide variety of configurations. UDFs must be easily installed within this environment, and must be able to run within all supported configurations. The Sybase IQ installer provides a default installation directory, but allows users to select a different installation directory. UDF developers should consider providing the same flexibility with the installation of the UDF libraries and associated SQL function definition scripts.

• Creating a user-defined function
  Learn how to create and configure external C/C++ user-defined functions (UDFs).
• User-defined function restrictions
  External C/C++ user-defined functions have some restrictions.
• Calling user-defined functions
  You can use a user-defined function, subject to permissions, any place you use a built-in nonaggregate function.
• Setting the dynamic library interface
  Specify the interface style to be used in the dynamically linkable library.
• Dropping user-defined functions
  Once you create a user-defined function, it remains in the database until it is explicitly removed. Only the owner of the function or a user with DBA authority can drop a function from the database.
• Granting and revoking permissions
  A user-defined function is owned by the user who created it, and only that user can execute it without permission. The owner can grant permissions to other users using the GRANT EXECUTE command.
• Maintenance of user-defined functions
  
• Compiling and linking source code to build dynamically linkable libraries
  Use compile and link switches when building dynamically linkable libraries for any user-defined function.
• Using Microsoft Visual Studio debugger for user-defined functions
  
• SQL data types
  UDF declarations support only certain SQL data types.