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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
OS Components & Operations
QDB Developer's Guide
QDB API Reference
QDB provides a comprehensive API for managing databases and accessing data.
qdb_cell_length()
Return the length of a cell's data

QNX Momentics IDE User's Guide
This User's Guide describes version 7.1 of the Integrated Development Environment (IDE) that's part of the QNX Momentics tool suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
- Quickstart Guide
- OS Components & Operations
  - Adaptive Partitioning User's Guide
  - Boot Optimization Guide
    The Boot Optimization Guide describes techniques you can use to reduce the time from your board's initial power on until you have a fully functional QNX system running on the board.
  - Building Embedded Systems
    The Building Embedded Systems guide is intended for developers who are developing or building BSPs for QNX Neutrino RTOS embedded systems.
  - Core Networking Stack User's Guide
    This guide introduces you to the QNX Neutrino Core Networking stack and its manager, io-pkt.
  - Customizing a BSP
    While QNX provides Board Support Packages (BSPs) for many common platforms and their individual variants, in some cases, you need a BSP for a board that QNX does not provide. If this is the case, you can modify a QNX BSP or develop your own.
  - Device Publishers Developer's Guide
  - High Availability Framework Developer's Guide
  - High-Performance Networking Stack (io-sock) User's Guide
    This guide contains instructions for implementing and using the QNX Neutrino High-Performance Networking Stack and its manager, io-sock.
  - Instant Device Activation
  - Migrating to QNX SDP 7.1
  - PCI Server User's Guide
  - Persistent Publish/Subscribe Developer's Guide
  - Platform-independent Publish/Subscribe Developer's Guide
    This guide is intended for application developers who want to use the Platform-independent Publish Subscribe (PiPS) framework to exchange information with other applications. First, the overall PiPS design and data-exchange model are explained. Then, tutorials on using PiPS are given. These tutorials cover key tasks such as selecting a publish-subscribe provider to use and writing plugins that read and write custom data types.
  - QDB Developer's Guide
    - Getting Started with QDB
      The QNX Database (QDB) server is a small-footprint, embeddable SQL database server. It is designed as an easy-to-configure QNX Neutrino resource manager.
    - QDB Command Line
      Configure and maintain QDB databases
    - QDB Client
      Execute SQL statements on QDB databases
    - QDB Application Example
      QDB provides methods for client applications to query a database and step through the query results. The sample program shown here provides a walkthrough of the sequence of QDB method calls necessary to connect to a QDB database, issue a query, read the data in the result set, and disconnect from the database.
    - Datatypes in QDB
      QDB databases, which are stored in SQLite files, allow any value stored in any database field to have one of five standard storage classes. The SQLite design doesn't enforce data typing on database columns but instead maps each input value to a storage class based on the column's type affinity (preference).
    - QDB Virtual Machine Opcodes
      QDB uses a virtual machine to execute SQL statements. You can configure QDB to list the opcodes of the programs generated to execute the SQL statements and you can trace program execution.
    - Writing User-Defined Functions
      QDB allows you to write your own functions for manipulating data. The QDB library includes several data structures and functions useful for defining custom functionality, while the SQLite API provides methods that your custom code can call to access arguments or set results.
    - QDB API Reference
      QDB provides a comprehensive API for managing databases and accessing data.
      - qdb_backup()
        Start a database backup
      - qdb_binding_t
        Information to bind data to an SQL statement variable
      - qdb_bkcancel()
        Cancel a database backup
      - qdb_cell()
        Return a cell's data
      - qdb_cell_length()
        Return the length of a cell's data
      - qdb_cell_type()
        Return a cell's datatype
      - qdb_collation()
        (Deprecated) Change the runtime configuration of all user-defined collation sequences
      - qdb_collation_ext()
        Change the runtime configuration of a user-defined collation sequence
      - qdb_column_decltype()
        Return a column's declared type
      - qdb_column_index()
        Return a column's index
      - qdb_column_name()
        Return a column's name
      - qdb_columns()
        Return the number of columns in a result set
      - qdb_connect()
        Connect to a database
      - qdb_data_source()
        Extract the data source for a database
      - qdb_disconnect()
        Disconnect from a database
      - qdb_freeresult()
        Free the result of an SQL statement
      - qdb_getdbsize()
        Return size information for a database, based on the page size and number of pages
      - qdb_getdbsize_bytes()
        Return size information for a database, based on the total bytes used and total bytes free
      - qdb_geterrcode()
        Return the last error code
      - qdb_geterrmsg()
        Return the last error string
      - qdb_getoption()
        Return the value for a database session option
      - qdb_getresult()
        Return the result of a SELECT statement
      - qdb_getresultoption()
        Return the value for a database session option when a SELECT command was issued
      - qdb_gettransstate()
        Return the transaction state for a database connection
      - qdb_interrupt()
        Interrupt long-running queries
      - qdb_last_insert_rowid()
        Return the primary key of the last inserted row
      - qdb_logmemstats()
        Log memory statistics for a database
      - qdb_mprintf()
        Print formatted output to a new string
      - qdb_parameters()
        Get or set database connection parameters
      - qdb_printmsg()
        Print data from a query result
      - qdb_query()
        Perform a database query
      - qdb_rowchanges()
        Return the number of rows affected by an SQL statement
      - qdb_rows()
        Return the number of rows in a result set
      - qdb_setbusytimeout()
        Set the busy timeout for a database connection
      - qdb_setoption()
        Set a database session option
      - qdb_snprintf()
        Print formatted output to a length-bounded string
      - qdb_statement()
        Execute SQL code on a database
      - qdb_stmt_decltypes()
        Get the declared column types for a prepared statement
      - qdb_stmt_exec()
        Execute a prepared statement
      - qdb_stmt_free()
        Free a prepared statement
      - qdb_stmt_init()
        Initialize a prepared statement
      - qdb_vacuum()
        Vacuum a database
      - qdb_vmprintf()
        Print formatted output to a new string
    - QDB SQL Reference
      QDB supports a subset of ANSI SQL-92.
    - fileset Reference
      Copy a file set
  - QNX Helpers Developer's Guide
    These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
  - SMMUMAN User's Guide
  - System Analysis Toolkit (SAT) User's Guide
  - System Architecture
    The System Architecture guide accompanies the QNX Neutrino RTOS and is intended for both application developers and end-users.
  - Technotes
  - User's Guide
    The QNX Neutrino User's Guide is intended for all users of a QNX Neutrino RTOS system, from system administrators to end users.
- Audio & Graphics API
- Multimedia
- Networking Middleware
- Programming
- Sensor Framework
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX Neutrino RTOS system and developers who want to create a QNX Neutrino resource manager free from vulnerabilities.
- Utilities & Libraries
QNX Hypervisor
The QNX Hypervisor allows you to run multiple OSs on a target system so you can separate critical and non-critical functions, support a wide variety of applications, and reduce hardware costs.
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX software in Amazon Web Services (AWS) and Microsoft Azure (Azure).
QNX Advanced Virtualization Frameworks User's Guide
This User's Guide is aimed at all systems integrators and developers who want to design and build embedded systems using the QNX Advanced Virtualization Frameworks.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

qdb_cell_length()

Return the length of a cell's data

Synopsis:

#include <qdb/qdb.h>

int qdb_cell_length( qdb_result_t *res, int row, int col );

Arguments:

res: A pointer to a result structure to check.
row: The row number of the cell, where the first row is 0.
col: The column number of the cell, where the first column is 0.

Library:

qdb

Description:

This function returns the length of the specified cell of a database query result. This is useful for variable-length datatypes, such as QDB_TEXT and QDB_BLOB. For QDB_TEXT, this function doesn't count the terminating null character.

Returns:

>=0: The length of the specified cell's data, in bytes.
-1: An error occurred (errno is set).

Classification:

QNX Neutrino


Safety:
Interrupt handler	No
Signal handler	No
Thread	Yes

Page updated: March 12, 2026