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Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
Informix® ODBC Driver Guide
The Informix® ODBC Driver Programmer's Manual serves as a user guide and reference for Informix ODBC Driver, which is the Informix implementation of the Microsoft™ Open Database Connectivity (ODBC) interface, Version 3.0.
Overview of HCL Informix® ODBC Driver
These topics introduce the Informix® ODBC Driver and describe its advantages and architecture. The topics also describe conformance, isolation and lock levels, libraries, and environment variables.
Partially supported and unsupported ODBC features
Informix® ODBC Driver supports partial implementation of several ODBC features.
Transaction processing
Informix® ODBC Driver implementation of transaction isolation levels and transaction modes is slightly different from the Microsoft™ ODBC implementation of these features.
Transaction isolation levels
Informix® ODBC Driver supports three transaction isolation levels for the Informix database server.

Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
- Change Data Capture API Programmer's Guide
  The Informix® Change Data Capture API Programmer's Guide describes how to program applications to process changed data from HCL Informix databases using the Informix Change Data Capture API.
- Embedded SQLJ for HCL Informix®
  The Informix® Embedded SQLJ User's Guide contains information about using Informix Embedded SQLJ.
- ESQL/C Guide
  The Informix® ESQL/C Programmer's Manual explains how to use Informix ESQL/C, the Informix implementation of Embedded Structured Query Language (SQL) for C (ESQL/C), to create client applications with database-management capabilities.
- GLS User's Guide
  The Informix® GLS User's Guide describes the Global Language Support (GLS) feature available in Informix products.
- API
  The Informix® GLS API Programmer's Guide describes the global language support (GLS) application programming interface (API) available in Informix ESQL/C and HCL Informix DataBlade® modules.
- Informix® Object Interface for C++ Guide
  The Informix® Object Interface for C++ Programmer's Guide describes how to develop HCL Informix client applications by using the object-oriented C++ programming language.
- Informix® ODBC Driver Guide
  The Informix® ODBC Driver Programmer's Manual serves as a user guide and reference for Informix ODBC Driver, which is the Informix implementation of the Microsoft™ Open Database Connectivity (ODBC) interface, Version 3.0.
  - Overview of HCL Informix® ODBC Driver
    These topics introduce the Informix® ODBC Driver and describe its advantages and architecture. The topics also describe conformance, isolation and lock levels, libraries, and environment variables.
    - What is HCL Informix® ODBC Driver?
      Open Database Connectivity (ODBC) is a specification for a database application programming interface (API).
    - ODBC component overview
      ODBC with the Informix® ODBC Driver includes several components.
    - HCL Informix® ODBC Driver with the DMR
      Informix® ODBC Driver includes a Driver Manager Replacement (DMR) library. The DMR replaces the driver manager on platforms where no driver manager is available.
    - HCL Informix® ODBC Driver components
      Informix® ODBC Driver includes the four components.
    - The HCL Informix® ODBC Driver API
      An application uses the Informix® ODBC Driver API to make a connection to a data source, send SQL statements to a data source, process result data dynamically, and terminate a connection.
    - Connection pooling
      Starting CSDK 4.50.xC2 onwards, Informix ODBC driver also supports Connection Pooling capabilities. One may decide to use either Connection Pooling capabilities provided by ODBC Driver Manager or newly added capabilities in Informix ODBC Driver
    - Global Language Support
      HCL Informix® products can support many languages, cultures, and code sets. Global Language Support (GLS) provides support for all language- and culture-specific information.
    - X/Open standard interface
      In addition to the standard ODBC functions, the Informix® ODBC Driver also supports the additional functions.
    - External authentication
      For HCL Informix® Version 10.0 and later, you can implement external authentication through the Informix ODBC Driver.
    - Bypass ODBC parsing
      You can bypass ODBC parsing by using several options.
    - BufferLength in character for SQLGetDiagRecW
      The SQLGetDiagRecW API returns diagnostic information in the output buffer, where the BufferLength parameter is the length of buffer allocated.
    - Informix® and ISAM error descriptions in SQLGetDiagRec
      The SQLGetDiagRec API returns diagnostic information in the output buffer, where the error description is for the HCL Informix® error message.
    - Improved performance for single-threaded applications
      You are likely to improve the performance of single-threaded applications by using the SINGLETHREADED connection parameter. The value is off by default.
    - Partially supported and unsupported ODBC features
      Informix® ODBC Driver supports partial implementation of several ODBC features.
      - Transaction processing
        Informix® ODBC Driver implementation of transaction isolation levels and transaction modes is slightly different from the Microsoft™ ODBC implementation of these features.
        Transaction isolation levels
        Informix® ODBC Driver supports three transaction isolation levels for the Informix database server.
        Changing the transaction mode
        You can change the transaction mode from its default of auto-commit to manual commit.
      - ODBC cursors
        Informix® ODBC Driver supports static and forward cursors but not dynamic and keyset-driven cursors.
      - ODBC bookmarks
        A bookmark is a value that identifies a row of data.
      - SQLBulkOperations
        Informix® ODBC Driver supports only the SQL_ADD argument of SQLBulkOperations.
      - SQLDescribeParam
        SQLDescribeParam is an ODBC API which returns metadata for the parameters of a query.
      - Unsupported Microsoft™ ODBC driver features
        Informix® ODBC Driver does not support implementation of the certain Microsoft™ ODBC driver features.
  - Configure data sources
    These topics explain how to configure a data source (DSN) on UNIX™ and Windows™ for Informix® ODBC Driver.
  - Data types
    These topics contain information about the data types that are supported by Informix® ODBC Driver.
  - Smart large objects
    These topics describe how to store, create, and access a smart large object; how to transfer smart-large-object data; how to retrieve the status of a smart large object; and how to read or write a smart large object to or from a file.
  - Rows and collections
    Rows and collections are composite values that consist of one or more elements.
  - Client functions
    These topics describe the Informix® ODBC Driver client functions. Use these functions to access and manipulate smart large objects and rows and collections.
  - Application tracking in ODBC
    Set the CLIENT_LABEL environment variable in CSDK 4.50.xC4 onwards to assign a character string to ODBC client session and identify that character string on the database server. You can use this variable to distinguish one database session from the other.
  - Improve application performance
    These topics suggest ways to improve performance of Informix® ODBC Driver applications.
  - Error messages
    These topics describe the Informix® ODBC Driver error messages.
  - Unicode
    These topics provide a brief overview of the Unicode standard and shows how it is used within ODBC applications.
  - ODBC Smart trigger
- .NET provider options
  The Data Server Provider for .NET DB2® provider option is the preferred Informix® provider for developing new applications.
- Informix® JDBC Driver Guide
  The Informix® JDBC Driver Programmer's Guide describes how to install, load, and use Informix JDBC Driver to connect to the Informix database from within a Java™ application or applet.
- Informix International Language Supplement (ILS) User Guide
  These topics include information about the translated user interface files for Informix® UNIX™ products, locales, and code set conversion tables
- Informix® OLE DB Provider Guide
  The Informix® OLE DB Provider Programmer's Guide describes the software requirements for using Informix OLE DB Provider, show how to install and configure the provider for your use, and explain how to use Informix OLE DB Provider to enable client applications, such as ActiveX Data Object (ADO) applications and web pages, to access data on the Informix server.

Transaction isolation levels

Informix® ODBC Driver supports three transaction isolation levels for the Informix® database server.

The following table lists the transaction isolation levels that Informix® ODBC Driver supports for the Informix® database server.


Database servers	Transaction isolation levels
HCL Informix®	SQL_TXN_READ_COMMITTED SQL_TXN_READ_UNCOMMITTED SQL_TXN_SERIALIZABLE

The default transaction isolation level is SQL_TXN_READ_COMMITTED. To change the transaction isolation level, call SQLSetConnectOption() with an fOption value of SQL_TXN_ISOLATION.

For more information about transaction isolation levels, see the SQL_DEFAULT_TXN_ISOLATION and SQL_TXN_ISOLATION_OPTION descriptions in the Informix® ODBC Driver Programmer's Manual.