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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.
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.
What is Informix® ESQL/C?
Time data types
These topics explain how to use date, datetime, and interval data types in the Informix® ESQL/C program.
The SQL DATETIME and INTERVAL data types
Converting data for datetime values
You can use the Informix® ESQL/C library functions dtcvasc(), dtcvfmtasc(), dttoasc(), and dttofmtasc() to explicitly convert between DATETIME column values and character strings.

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.
  - What is Informix® ESQL/C?
    - Informix® ESQL/C programming
    - Compile programs
    - Informix® ESQL/C data types
      These topics contain information about the correspondence between SQL and C data types and how to handle data types in the Informix® ESQL/C program.
    - Character and string data types
      These topics explain how to use character data types in the Informix® ESQL/C program.
    - Numeric data types
    - Time data types
      These topics explain how to use date, datetime, and interval data types in the Informix® ESQL/C program.
      - The SQL DATE data type
      - DATE library functions
      - The SQL DATETIME and INTERVAL data types
        The datetime data type
        Use the datetime data type to declare host variables for database values of type DATETIME. You specify the accuracy of the datetime data type with a qualifier.
        The interval data type
        Use the interval data type to declare host variables for database values of type INTERVAL.
        Macros for datetime and interval data types
        Fetch and insert DATETIME and INTERVAL values
        ANSI SQL standards for DATETIME and INTERVAL values
        Converting data for datetime values
        You can use the Informix® ESQL/C library functions dtcvasc(), dtcvfmtasc(), dttoasc(), and dttofmtasc() to explicitly convert between DATETIME column values and character strings.
        Converting data for interval values
        You can use the Informix® ESQL/C library functions incvasc(), incvfmtasc(), intoasc(), and intofmtasc() to explicitly convert between INTERVAL column values and character strings.
      - Support of non-ANSI DATETIME formats
        Informix® ESQL/C supports conversions from a data-time string in a non-ANSI format to the DATETIME data type. This conversion makes it easier to upgrade from Asian Language Support (ALS) client/server products to Global Language Support (GLS) client/server products.
      - DATETIME and INTERVAL library functions
    - Simple large objects
      A simple large object is a large object that is stored in a blobspace on disk and is not recoverable.
    - Smart large objects
      A smart large object is a data type that stores large, non-relational data objects such as images, sound clips, documents, graphics, maps and other large objects, and allows you to perform read, write, and seek operations on those objects.
    - Complex data types
      These topics explain how to use collection and row data types in the Informix® ESQL/C program.
    - Opaque data types
      These topics explain how to use the lvarchar, fixed binary, and var binary data types to access an opaque data type from the Informix® ESQL/C program. Use these Informix ESQL/C data types to represent an opaque data type as it is transferred to and from Informix.
  - Database server communication
  - Dynamic SQL
  - Appendixes
    This section contains additional reference information.
- 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.
- .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.

Converting data for datetime values

You can use the Informix® ESQL/C library functions dtcvasc(), dtcvfmtasc(), dttoasc(), and dttofmtasc() to explicitly convert between DATETIME column values and character strings.

About this task

For example, you can perform conversions between the DATETIME and DATE data types with Informix® ESQL/C library functions and intermediate strings.

To convert a DATETIME value to a DATE value:

Procedure

Use the dtextend() function to adjust the DATETIME qualifier to year to day.
Apply the dttoasc() function to create a character string in the form yyyy-mm-dd.
Use The rdefmtdate() function with a pattern argument of yyyy-mm-dd to convert the string to a DATE value.