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Extending Informix®
Beyond standard relational database objects, HCL Informix® can be extended to handle specialized data types, access methods, routines, and other objects. Informix includes many built-in extensions that are fully integrated in the database server. Informix also provides DataBlade® modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for Informix.
Creating extensions
You can create user-defined data types, routines, access methods, and other database objects to suit your needs. You can use application programming interfaces to write user-defined routines and applications that access data in Informix® databases.
DataBlade® API Programmer's Guide
The Informix® DataBlade® API Programmer's Guide describes information about the DataBlade API, the C-language application programming interface (API) provided with HCL Informix.
Data manipulation
Numeric data types
This section describes these numeric data types and the functions that the DataBlade® API supports to process numeric data.
Fixed-point data
Fixed-point data is a decimal value with a fixed number of digits to the right and left of the decimal point. The fixed number of digits to the right of the decimal point is called the scale of the value. The total number of digits in the fixed-point value is called the precision of the value.
Fixed-point binary representations
The decimal.h header file
The decimal.h header file contains definitions for use with the DECIMAL and MONEY data types.
The decimal macros

Extending Informix®
Beyond standard relational database objects, HCL Informix® can be extended to handle specialized data types, access methods, routines, and other objects. Informix includes many built-in extensions that are fully integrated in the database server. Informix also provides DataBlade® modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for Informix.
- Informix® extensions and DataBlade® modules
  These topics describe how to use built-in database extensions and separately installed DataBlade® modules.
- Creating extensions
  You can create user-defined data types, routines, access methods, and other database objects to suit your needs. You can use application programming interfaces to write user-defined routines and applications that access data in Informix® databases.
  - DataBlade® API Programmer's Guide
    The Informix® DataBlade® API Programmer's Guide describes information about the DataBlade API, the C-language application programming interface (API) provided with HCL Informix.
    - DataBlade® API overview
    - Data manipulation
      - Numeric data types
        This section describes these numeric data types and the functions that the DataBlade® API supports to process numeric data.
        Integer data
        Integer data is a value with no digits to the right of the decimal point. The DataBlade® API provides support for integer values in both their text and binary representations.
        Fixed-point data
        Fixed-point data is a decimal value with a fixed number of digits to the right and left of the decimal point. The fixed number of digits to the right of the decimal point is called the scale of the value. The total number of digits in the fixed-point value is called the precision of the value.
        Fixed-point text representations
        The text representation of a fixed-point value is a quoted string that contains a series of digits. The DataBlade® API supports a text representation for both decimal and monetary values.
        Fixed-point binary representations
        DECIMAL data type: Fixed-point data
        When you define a column with the DECIMAL(p,s) data type, the syntax of this definition specifies a fixed-point value for the column. This value has a total of p (<= 32) significant digits (the precision) and s (<= p) digits to the right of the decimal point (the scale).
        MONEY data type
        When you define a column with the MONEY(p) data type, it has a total of p (<= 32) significant digits (the precision) and a scale of 2 digits.
        The decimal.h header file
        The decimal.h header file contains definitions for use with the DECIMAL and MONEY data types.
        Internal fixed-point decimal format
        The DECIMAL and MONEY data types store fixed-point values in a proprietary internal format for HCL Informix®: the dec_t structure. This structure holds the internal (binary) format of a DECIMAL or MONEY value.
        The decimal macros
        ESQL/C DECIMAL-type functions
        Transfer fixed-point data (Server)
        Convert decimal data
        Both the DataBlade® API library and the Informix® ESQL/C library provide functions that convert the binary representation for DECIMAL (mi_decimal) or MONEY (mi_money) values.
        Perform operations on decimal data
        The Informix® ESQL/C function library provides functions to perform arithmetic operations on DECIMAL (mi_decimal) and MONEY (mi_money) values.
        Obtain fixed-point type information
        The DataBlade® API provides functions to obtain the scale and precision of a fixed-point (DECIMAL and MONEY) data type.
        Floating-point data
        A floating-point value is a large decimal value that is stored in a fixed field width. Because the field width is fixed, a floating-point number that is larger than the field width only retains its most significant digits. That is, digits that do not fit into the fixed width are dropped (rounded or truncated).
        Format numeric strings
        The Informix® ESQL/C library provides special functions that enable you to format numeric expressions as strings.
      - Date and time data types
        This section describes the date and time data types and the functions that the DataBlade® API supports to process date and time data.
      - Complex data types
        This section describes the complex data types and the functions that the DataBlade® API supports to process collection and row-type data.
      - Smart large objects
    - Database access
    - Create user-defined routines
    - Appendix
      This section contains additional reference information.
  - DataBlade® API Function Reference
    The Informix® DataBlade® API Function Reference describes the DataBlade API functions and the subset of Informix ESQL/C functions that the DataBlade API supports.
  - DataBlade® Developers Kit
    The DataBlade® Developers Kit (DBDK) guides contain information about the tools you can use to develop and package DataBlade modules, which extend the functionality of HCL Informix® databases.
  - J/Foundation Developer's Guide
    The J/Foundation Developer's Guide describes how to write user-defined routines (UDRs) in the Java™ programming language for Informix®.
  - R-Tree Index User's Guide
    The Informix® R-Tree Index User's Guide describes the HCL Informix R-tree secondary access method and how to access and use its components.
  - User-Defined Routines and Data Types Developer's Guide
    The Informix® User-Defined Routines and Data Types Developer's Guide describes how to define new data types and enable user-defined routines (UDRs) to extend HCL Informix.
  - Virtual-Table Interface Guide
    The Informix® Virtual-Table Interface Programmer's Guide explains how to create a primary access method with the Virtual-Table Interface (VTI) so that users have a single SQL interface to HCL Informix tables and to data that does not conform to the storage scheme of HCL Informix.
  - Virtual-Index Interface Guide
    The Informix® Virtual-Index Interface Programmer's Guide explains how to create a secondary access method with the Virtual-Index Interface (VII) to extend the built-in indexing schemes of HCL Informix typically with a DataBlade® module.

The decimal macros

The decimal.h header file also includes the following macros that might be useful in a DataBlade® API module.


Decimal macro	Description
DECLEN(p, s)	Calculates the minimum number of bytes required to hold the DECIMAL(p,s) value
DECPREC(size)	Calculates a default precision given the number of bytes (size) used to store the number
PRECTOT(dec)	Returns the total precision of the dec value
PRECDEC(dec)	Returns the scale of the dec value
PRECMAKE(p, s)	Creates a precision value from the specified total precision (p) and scale (s) For a complete list of decimal macros, consult the decimal.h header file that is installed with your database server. This header file is in the incl/public subdirectory of the INFORMIXDIR directory.