Issue database queries and retrieve results

To interact with a database, your C++ client application uses the operation classes of the HCL Informix® Object Interface for C++. 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 HCL Informix Object Interface for C++, each suitable for different application requirements.

Parent topic: Informix Object Interface for C++ Guide