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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
Fetch and insert DATETIME and INTERVAL values
Fetch and insert into interval host variables

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
        Fetch and insert into datetime host variables
        Fetch and insert into interval host variables
        Implicit data conversion
        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.

Fetch and insert into interval host variables

When an application uses an interval host variable to fetch or insert an INTERVAL value, Informix® ESQL/C must find a valid qualifier in the interval host variable. Informix® ESQL/C takes one of the following actions, based on the value of the in_qual field of the intrvl_t structure that is associated with the host variable:

When the in_qual field contains a valid qualifier, Informix® ESQL/C checks it for compatibility with the qualifier from the INTERVAL column value.
The two qualifiers are compatible if they belong to the same interval class: either year to month or day to fraction. If the qualifiers are incompatible, Informix® ESQL/C sets the SQLSTATE status variable to an error-class code (and SQLCODE is set to a negative value) and the select, update, or insert operation fails.
If the qualifiers are compatible but not the same, Informix® ESQL/C extends the column value to match the in_qual qualifier. Extending is the operation of adding or dropping fields within one of the interval classes of an INTERVAL value to make it match a given qualifier. You can explicitly extend INTERVAL values with the Informix® ESQL/C invextend() function.
When the in_qual field does not contain a valid qualifier, Informix® ESQL/C takes different actions for a fetch and an insert:
- For a fetch, if the in_qual field contains zero or is not a valid qualifier, Informix® ESQL/C uses the INTERVAL column value and its qualifier to initialize the interval host variable.
- For an insert, if the in_qual field is not compatible with the INTERVAL column or if it does not contain a valid value, Informix® ESQL/C cannot perform the insert or update operation.
  Informix® ESQL/C sets the SQLSTATE status variable to an error-class code (and SQLCODE is set to a negative value) and the update or insert operation on the INTERVAL column fails.