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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.
Dynamic SQL
An sqlda structure
An sqlda structure is a dynamic-management structure that can hold data that is either returned from or sent to the database server by a prepared statement. It is a C structure defined in the sqlda.h header file.
Manage an sqlda structure
Define an sqlda structure
The Informix® ESQL/C sqlda.h header file defines the sqlda structure.

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?
  - Database server communication
  - Dynamic SQL
    - Using dynamic SQL
    - Determine SQL statements
      If you do not know until run time what SQL statement to execute, you can dynamically determine that statement with the DESCRIBE statement and use a dynamic-management structure to hold any values that the statement sends to or receives from the database server.
    - A system-descriptor area
      A system-descriptor area is a dynamic-management structure that can hold data that a prepared statement either returns from or sends to the database server. A system-descriptor area conforms to X/Open standards.
    - An sqlda structure
      An sqlda structure is a dynamic-management structure that can hold data that is either returned from or sent to the database server by a prepared statement. It is a C structure defined in the sqlda.h header file.
      - Manage an sqlda structure
        Define an sqlda structure
        The Informix® ESQL/C sqlda.h header file defines the sqlda structure.
        Allocate memory for the sqlda structure
        Initialize the sqlda structure
        Allocate memory for column data
        Assign and obtain values from an sqlda structure
        When you use the sqlda structure with dynamic SQL, you must transfer information in and out of it with C-language statements.
        Specify input parameter values
        Put column values into an sqlda structure
        Free memory allocated to an sqlda structure
      - An sqlda structure to execute SQL statements
        Use an SQL descriptor-area (sqlda) structure to execute SQL statements that contain unknown values.
      - Handling an unknown select list
      - Handling unknown return values
        You can use an sqlda structure to save values that a dynamically executed user-defined function returns.
      - Handling an unknown column list
        You can use an sqlda structure to handle the INSERT...VALUES statement
      - Handling a parameterized SELECT statement
        You can handle a parameterized SELECT statement with an sqlda structure.
      - Handling a parameterized user-defined routine
      - Handling a parameterized UPDATE or DELETE statement
  - 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.

Define an sqlda structure

The Informix® ESQL/C sqlda.h header file defines the sqlda structure.

To define an sqlda structure, the Informix® ESQL/C program must take the following actions:

Include the sqlda.h header file to provide the declaration for sqlda in your program
The Informix® ESQL/C preprocessor automatically includes the sqlhdr.h file, which includes the sqlda.h header file.
Declare a variable name as a pointer to the sqlda structure
The following line of code declares the da_ptr variable as an sqlda pointer:
```
struct sqlda *da_ptr;
```

Important: The pointer to an sqlda structure is not the Informix® ESQL/C host variable. Therefore, you do not need to precede the statement declaration with either the keywords EXEC SQL or a dollar ($) symbol. Furthermore, in the program blocks you do not precede any references to the pointer with a colon (:) or a dollar ($) symbol.