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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® 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.
Issue database queries and retrieve results
To interact with a database, your C++ client application uses the operation classes of the . These classes have methods for opening database connections, submitting queries, and manipulating database cursors. This section describes how to use these methods.
Issue queries
There are a number of different ways to issue SQL queries in the , each suitable for different application requirements.
Using ITRoutineManager
The ITRoutineManager class provides an alternative way to execute server routines. The functionality of the ITRoutineManager class is only supported with HCL Informix® databases.

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.
  - Architecture of the object interface for C++
    The encapsulates HCL Informix® database server features into a class hierarchy.
  - Issue database queries and retrieve results
    To interact with a database, your C++ client application uses the operation classes of the . These classes have methods for opening database connections, submitting queries, and manipulating database cursors. This section describes how to use these methods.
    - Using operation classes
      The csql.cpp example is a small application that uses the ITQuery and ITConnection classes to provide a simple command-line interface that accepts SQL commands from the standard input, transmits the commands to the database, and the results are displayed.
    - Create connections
      To specify connection parameters (system, database, user name, and password) when creating a connection, your application creates an instance of the ITDBInfo class. If the application uses the default connection parameters, you can create a connection without the use an instance of the ITDBInfo class.
    - Find system names and database names
      Many client applications determine what database to use at run time, sometimes allowing users to select from alternatives. You can use the ITSystemNameList class and the ITDatabaseNameList class to retrieve lists of HCL Informix® servers and databases.
    - Manage errors
    - Connection transaction states
      A connection to a database is said to be in one of a number of transaction states. Transaction states show how queries submitted on the connection are committed. Some server operations can only take place within a transaction. For example, updateable cursors can only be opened within a transaction.
    - Issue queries
      There are a number of different ways to issue SQL queries in the , each suitable for different application requirements.
      - When to use the different ITQuery methods
        This section describes how to use the query methods appropriately.
      - Query method example
        The queryex.cpp example demonstrates use of the ExecForStatus, ExecOneRow, and ExecToSet methods.
      - Using prepared statements
        Prepared statements can be used to perform INSERT, UPDATE, and DELETE functions efficiently and to pass binary data as parameters. The encapsulates prepared statement functionality in the ITStatement class.
      - Using cursors
        Cursors can be used to efficiently perform SELECT statements with parameters and to pass binary data as parameters. Cursors can also be used to update database tables. The encapsulates cursor functionality into the ITCursor class.
      - Using the large object manager
        The ITLargeObjectManager class performs simple operations on large objects such as creating, opening, reading, and seeking.
      - Using ITRoutineManager
        The ITRoutineManager class provides an alternative way to execute server routines. The functionality of the ITRoutineManager class is only supported with HCL Informix® databases.
  - Access data values
    This section describes the specific value interfaces in detail, and shows how to modify value objects and extract information through the value interfaces into host variables in your application.
  - Create and extend value objects
    When you retrieve values from the HCL Informix® database by using the , the values are returned as value objects. Value objects are created by the Object Interface for C++ by using an extensible class factory that maps Informix data types to C++ objects.
  - Operation class reference
    This section is an alphabetized reference that lists and describes the operation classes. Each class has an assignment operator and a copy constructor, which are not listed in the tables of methods.
  - Value interface reference
    This section lists and describes the value interfaces. The ITFactoryList and ITPreserveData classes provide support for value interfaces.
  - Appendixes
    This section contains additional reference information.
- 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.

Using ITRoutineManager

The ITRoutineManager class provides an alternative way to execute server routines. The functionality of the ITRoutineManager class is only supported with HCL Informix® databases.

When using ITRoutineManager, a connection does not have to be checked out to get or execute a routine (and a value object, therefore, can use it), and the execution of the routine commences faster since there is no SQL to parse.

The following excerpts from routine.cpp illustrate the use of ITRoutineManager.

To use ITRoutineManager, the application creates an instance of it on an open connection object.
```
ITRoutineManager routine(conn);
```
The GetRoutine() method retrieves the function descriptor for the function whose signature is passed as an argument.
```
ITBool bret = routine.GetRoutine("function sum(int,int)");
```
The application sets parameter values by using ITValue::FromPrintable().
```
val = routine.Param(0);
val->FromPrintable("1");
val->Release();
```
It can also set parameter values by using ITRoutineManager::SetParam().
The routine is executed with ExecForValue(), which returns a pointer to ITValue corresponding to the return value of the routine.
```
val2 = routine.ExecForValue();
```
A Release() call releases the ITValue instance.
```
val2->Release();
}
```