C and C++ routines

C and C++ routines are external routines that are created by executing a CREATE PROCEDURE, CREATE FUNCTION, or CREATE METHOD statement that references a library built from C or C++ source code as its external code body.

C and C++ routines can optionally execute SQL statements by including embedded SQL statements.

The following terms are important in the context of C and C++ routines:

CREATE statement: The SQL language CREATE statement used to create the routine in the database.
Routine-body source code: The source code file containing the C or C++ routine implementation that corresponds to the CREATE statement EXTERNAL clause specification.
Precompiler: The database utility that pre-parses the routine source code implementation to validate SQL statements contained in the code and generates a package.
Compiler: The programming language specific software required to compile and link the source code implementation.
Package: The file containing the runtime access path information that the database manager uses at routine runtime to execute the SQL statements contained in the routine code implementation.
Routine library: A file that contains the compiled form of the routine source code. In Windows this is sometimes called a DLL, because these files have .dll file extensions.

Before developing a C or C++ routine, it is important to both understand the basics of routines and the unique features and characteristics specific to C and C++ routines. An understanding of the Embedded SQL API and the basics of embedded SQL application development is also important. To learn more about these subjects, refer to the following topics:

External routines
Embedded SQL
Include files for C and C++ routines
Parameters in C and C++ routines
Restrictions on C and C++ routines

Developing a C or C++ routines involves following a series of step by step instructions and looking at C or C++ routine examples. Refer to:

Creating C and C++ routines
Examples of C procedures
Examples of C user-defined functions