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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.
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.
Functions for smart large objects
This section describes each client function that the driver provides for smart large objects.
The ifx_lo_truncate() function
The ifx_lo_truncate() function truncates a smart large object at the specified position.

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.
  - 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.
    - Call a client function
      This section describes the syntax of client functions, their input/output arguments, return values, and SQL_BIGINT.
    - Functions for smart large objects
      This section describes each client function that the driver provides for smart large objects.
      - The ifx_lo_alter() function
        The ifx_lo_alter() function alters the storage characteristics of a smart large object.
      - The ifx_lo_close() function
        The ifx_lo_close() function closes a smart large object.
      - The ifx_lo_col_info() function
        The ifx_lo_col_info() function updates a smart-large-object specification structure with column-level storage characteristics.
      - The ifx_lo_create() function
        The ifx_lo_create() function creates and opens a new smart large object.
      - The ifx_lo_def_create_spec() function
        The ifx_lo_def_create_spec() function creates a smart-large-object specification structure.
      - The ifx_lo_open() function
        The ifx_lo_open() function opens a smart large object.
      - The ifx_lo_read() function
        The ifx_lo_read() function reads data from an open smart large object.
      - The ifx_lo_readwithseek() function
        The ifx_lo_readwithseek() function performs a seek operation and then reads data from an open smart large object.
      - The ifx_lo_seek() function
        The ifx_lo_seek() function sets the file position for the next read or write operation on an open smart large object.
      - The ifx_lo_specget_estbytes() function
        The ifx_lo_specget_estbytes() function gets the estimated number of bytes from a smart-large-object specification structure.
      - The ifx_lo_specget_extsz() function
        The ifx_lo_specget_extsz() function gets the allocation extent from a smart-large-object specification structure.
      - The ifx_lo_specget_flags() function
        The ifx_lo_specget_flags() function gets the create-time flags from a smart-large-object specification structure.
      - The ifx_lo_specget_maxbytes() function
        The ifx_lo_specget_maxbytes() function gets the maximum number of bytes from a smart-large-object specification structure.
      - The ifx_lo_specget_sbspace() function
        The ifx_lo_specget_sbspace() function gets the sbspace name from a smart-large-object specification structure.
      - The ifx_lo_specset_estbytes() function
        The ifx_lo_specset_estbytes() function sets the estimated number of bytes in a smart-large-object specification structure.
      - The ifx_lo_specset_extsz() function
        The ifx_lo_specset_extsz() function sets the allocation extent size in a smart-large-object specification structure.
      - The ifx_lo_specset_flags() function
        The ifx_lo_specset_flags() function sets the create-time flags in a smart-large-object specification structure.
      - The ifx_lo_specset_maxbytes() function
        The ifx_lo_specset_maxbytes() function sets the maximum number of bytes in a smart-large-object specification structure.
      - The ifx_lo_specset_sbspace() function
        The ifx_lo_specset_sbspace() function sets the sbspace name in a smart-large-object specification structure.
      - The ifx_lo_stat() function
        The ifx_lo_stat() function initializes a smart-large-object status structure.
      - The ifx_lo_stat_atime() function
        The ifx_lo_stat_atime() function retrieves the last access time for a smart large object.
      - The ifx_lo_stat_cspec() function
        The ifx_lo_stat_cspec() function retrieves a smart-large-object specification structure.
      - The ifx_lo_stat_ctime() function
        The ifx_lo_stat_ctime() function retrieves the time of the last change of a smart large object.
      - The ifx_lo_stat_refcnt() function
        The ifx_lo_stat_refcnt() function retrieves the number of references to a smart large object.
      - The ifx_lo_stat_size() function
        The ifx_lo_stat_size() function retrieves the size of a smart large object.
      - The ifx_lo_tell() function
        The ifx_lo_tell() function retrieves the current file or seek position for an open smart large object.
      - The ifx_lo_truncate() function
        The ifx_lo_truncate() function truncates a smart large object at the specified position.
      - The ifx_lo_write() function
        The ifx_lo_write() function writes data to an open smart large object.
      - The ifx_lo_writewithseek() function
        The ifx_lo_writewithseek() function performs a seek operation and then writes data to an open smart large object.
    - Functions for rows and collections
      This section describes each client function that Informix® ODBC Driver provides for 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.

The ifx_lo_truncate() function

The ifx_lo_truncate() function truncates a smart large object at the specified position.

Syntax

ifx_lo_truncate(lofd, offset)

Arguments

The function accepts the following arguments.


Argument	Type	Use	Description
lofd	SQL_INTEGER	Input	Smart-large-object file descriptor
offset	SQL_BIGINT	Input	End of the smart large object. If this value exceeds the end of the smart large object, the function extends the smart large object. If this value is less than the end of the smart large object, the database server reclaims all storage from the offset position to the end of the smart large object. Instead of using the default Informix® ODBC Driver C data type of SQL_C_CHAR for offset, use SQL_C_LONG or SQL_C_SHORT.

Usage

The ifx_lo_truncate() function sets the end of a smart large object to the location that the offset argument specifies.