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.
Database access
Execute SQL statements
One basic task of a module is to send SQL statements to the database server for execution.
Retrieving query data
Obtain column values
Access the columns
The mi_value() and mi_value_by_name() functions access the row structure for the current row. The current row is in the cursor that is associated with the current statement. Because a current statement is associated with a connection, you must pass a connection descriptor into mi_value() or mi_value_by_name() to identify the row to access.
Interpret column-value status
The mi_value() and mi_value_by_name() functions return a value status, which identifies how to interpret the column value that these functions pass back.

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
    - Database access
      - Connection handling
        This section describes how to initialize, establish, and close connections.
      - Execute SQL statements
        One basic task of a module is to send SQL statements to the database server for execution.
        Execute SQL statements
        To execute an SQL statement, a module must send the SQL statement to the database server, where the statement is executed.
        Process statement results
        Retrieving query data
        Obtain row information
        A row descriptor (MI_ROW_DESC) contains information about the columns in a row.
        Obtain column information
        When you have a row descriptor for the row, you can obtain information about the columns with the row-descriptor access functions.
        Retrieve rows
        Obtain column values
        Execute the column-value loop
        Access the columns
        The mi_value() and mi_value_by_name() functions access the row structure for the current row. The current row is in the cursor that is associated with the current statement. Because a current statement is associated with a connection, you must pass a connection descriptor into mi_value() or mi_value_by_name() to identify the row to access.
        Pass in the value buffer
        To obtain the column value, you must pass in a pointer to a value buffer as an argument to mi_value() or mi_value_by_name(). The value buffer is the place that these functions put the column value that they retrieve from the current row. Both mi_value() and mi_value_by_name() represent a column value as a pointer to an MI_DATUM structure.
        Interpret column-value status
        The mi_value() and mi_value_by_name() functions return a value status, which identifies how to interpret the column value that these functions pass back.
        Obtain normal values
        The mi_value() and mi_value_by_name() functions return the MI_NORMAL_VALUE value status for a column with any data type other than a row type or collection. Therefore, these functions return MI_NORMAL_VALUE for columns that have a built-in data type, smart large object, opaque type, or distinct type.
        Obtain NULL values
        The mi_value() and mi_value_by_name() functions return the MI_NULL_VALUE value status for a column that contains the SQL NULL value. These functions return MI_NULL_VALUE for columns of any data type.
        Obtain row values
        Obtain collection values
        For a collection, the value that the mi_value() and mi_value_by_name() functions return depends on whether the control mode for the query data is text or binary representation.
        Example: The get_data() function
        Complete execution
        The provides functions to complete execution of the current statement.
        Inserting data into the database
        To insert a row of data into a database, you must execute the INSERT statement.
        Save sets
        Save sets provide a mechanism for a module to access several rows simultaneously.
      - Execute user-defined routines
        This section provides information about how to call a user-defined routine (UDR).
      - Exceptions and events
        This section describes exceptions and events, and explains how to handle them in modules.
      - XA-compliant external data sources
    - 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.

Interpret column-value status

The mi_value() and mi_value_by_name() functions return a value status, which identifies how to interpret the column value that these functions pass back.

The following table shows the kinds of column values that these functions can identify.


Type of column value	Value-status constant	More information
A built-in, opaque, or distinct data type	MI_NORMAL_VALUE	Obtain normal values
An SQL NULL value	MI_NULL_VALUE	Obtain NULL values
A row type	MI_ROW_VALUE	Obtain row values
A collection	MI_COLLECTION_VALUE	Obtain collection values

You can use a switch statement based on these value-status constants to determine how to handle the column value.