Welcome
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 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.
Programmer's Guide
The HCL® Informix® DataBlade® API Programmer's Guide describes information about the , 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 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.

HCL Informix® V15.0.0 documentation
Welcome to the documentation for HCL Informix® 15.0.0 and related client tools and products.
Product overview
HCL Informix® is a fast and scalable database server that manages traditional relational, object-relational, and dimensional databases. Its small footprint and self-managing capabilities are suited to embedded data-management solutions.
Installing
These topics describe how to install HCL Informix® database servers, client products, and modules.
Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
Migrating and upgrading
You can upgrade to the 15.0.0 release of HCL Informix® or migrate from other database servers to Informix. Upgrading is an in-place migration method that uses your existing hardware and operating system software. Some changes to the Informix database server can affect upgrading from a previous release.
Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
Embedding Informix®
When you embed HCL Informix®, you can use enterprise-class high-availability and high performance with embeddability features such as easy programmability, a small disk and memory footprint, and silent deployment.
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 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 modules
  These topics describe how to use built-in database extensions and separately installed 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.
  - Programmer's Guide
    The HCL® Informix® DataBlade® API Programmer's Guide describes information about the , the C-language application programming interface (API) provided with HCL Informix.
    - overview
    - Data manipulation
      - Numeric data types
        This section describes these numeric data types and the functions that the supports to process numeric data.
        Integer data
        Integer data is a value with no digits to the right of the decimal point. The 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 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 library and the library provide functions that convert the binary representation for DECIMAL (mi_decimal) or MONEY (mi_money) values.
        Perform operations on decimal data
        The function library provides functions to perform arithmetic operations on DECIMAL (mi_decimal) and MONEY (mi_money) values.
        Obtain fixed-point type information
        The 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 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 supports to process date and time data.
      - Complex data types
        This section describes the complex data types and the functions that the supports to process collection and row-type data.
      - Smart large objects
    - Database access
    - Create user-defined routines
    - Appendix
      This section contains additional reference information.
  - Function Reference
    The IBM® Informix® DataBlade® API Function Reference describes the functions and the subset of functions that the supports.
  - Developers Kit
    The Developers Kit (DBDK) guides contain information about the tools you can use to develop and package modules, which extend the functionality of HCL Informix® databases.
  - J/Foundation Developer's Guide
    The HCL® 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 HCL® 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 HCL® 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 IBM® 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 IBM® 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 module.
Data warehousing
In addition to designing and implementing Informix® dimensional databases, you can use tools to create data warehouse applications and optimize your data warehouse queries.
Designing databases
The first step in creating a relational database is to construct a data model, which is a precise, complete definition of the data you want to store. After you prepare your data model, you must implement it as a database and tables. To implement your data model, you first select a data type for each column and then you create a database and tables and populate the tables with data. You can also implement fragmentation strategies and control access to your data.
JSON compatibility
You can use the popular JSON-oriented query language created by MongoDB to interact with data stored in HCL Informix®.
Security
You can secure your Informix® database server and the data that is stored in your Informix databases. You can encrypt data, secure connections, control user privileges and access, and audit data security.
SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
Troubleshooting HCL Informix®
Several troubleshooting techniques, tools, and resources are available for resolving problems that you encounter in your HCL Informix® database server environment.

The decimal.h header file

The decimal.h header file contains definitions for use with the DECIMAL and MONEY data types.

This header file defines the following items:

The dec_t typedef
The decimal macros
The DECIMAL-type functions of the library

The mitypes.h header file automatically includes decimal.h. In turn, the milib.h header file automatically includes mitypes.h, and mi.h automatically includes milib.h. Therefore, you automatically have access to the dec_t structure, the mi_decimal and mi_money data types, any of the decimal macros, or any of the DECIMAL-type functions when you include mi.h in your module.