dart_odbc

A Dart package for interacting with ODBC databases. It allows you to connect to ODBC data sources and execute SQL queries directly from your Dart applications.

This package is inspired by the obsolete odbc package by Juan Mellado.

Usage

• Instanciate the ODBC class by providing the path to the odbc driver on the host machine

  final odbc = DartOdbc(
    '/path/to/the/odbc/driver',
    version=SQL_OV_ODBC3_80 // optional
  );

Path to ODBC Driver

Path to the ODBC driver can be found in the ODBC driver manager. In windows this is a .dll file that is there in the installation folder of the ODBC driver. In linux this has an extension of .so. In macos this should have an extension of .dylib.

version

The ODBC version can be specified using the version parameter. Definitions for these values can be found in the LibODBC class. Please note that some drivers may not work properly with manually setting version.

• Connect to the database by providing the DSN (Data Source Name) configured in the ODBC Driver Manager

  await odbc.connect(
    dsn: '<your_dsn>',
    username: 'db_username',
    password: 'db_password',
  );

• Or connect to the database via connection string

  await odbc.connectWithConnectionString(
    "DRIVER={Microsoft Excel Driver (*.xls, *.xlsx, *.xlsm, *.xlsb)};DBQ=C:\Users\Computer\AppData\Local\Temp\test.xlsx;"
  );

DSN (Data Source Name)

This is the name you gave when setting up the driver manager. For more information, visit this page from the MySQL Documentation

• In case the path privided to the driver is invalid or there is any issue with setting up the environment/connecting to the database, an Exception will be thrown when intanciating the ODBC or connecting to the database.
• Execute your queries directly as follows

  final result = await odbc.execute("SELECT 10");

Executing prepared statements

• Prepared statements can be used to prevent SQL Injection
• Example query

  final List<Map<String, dynamic>> result = await odbc.execute(
    'SELECT * FROM USERS WHERE UID = ?',
    params: [1],
  );

Providing configuration for result set columns

• The abstraction layer of DartOdbc should be able to handle output for most queries
• But output for columns with very long column size or uncommon data types could get corrupted due to issues in default memory allocation
• Thes can be handled by providing the ColumnType in the columnConfig parameter of the execute method on DartOdbc class
• Please refer the following example

  // Assume a table like this
  // +-----+-------+-------------+
  // | UID | NAME  | DESCRIPTION |
  // +-----+-------+-------------+
  // | 1   | Alice |             |
  // | 2   | Bob   |             |
  // +-----+-------+-------------+
  // The name is a column of size 150
  // The description is a column of size 500

  result = await odbc.execute(
    'SELECT * FROM USERS WHERE UID = ?',
    params: [1],

    /// The column config can be provided as this.
    /// But for most cases this config is not necessary
    /// This is only needed when the data fetching is not working as expected
    /// Only the columns with issues need to be provided
    columnConfig: {
      'NAME': ColumnType(size: 150),
      'DESCRIPTION': ColumnType(type: SQL_C_WCHAR, size: 500),
    },
  );

• Result will be a Future of List of Map objects (Future<List<Map<String, dynamic>>>) where each Map represents a row. If anything goes wrong an ODBCException will be thrown

Get Tables

final List<Map<String, String>> tables = await odbc.getTables();

Disconnecting from the database

• Finally, don't forget to disconnect from the database and free resources.

  await odbc.disconnect();

Accessing ODBC diver bindings directly

• Native ODBC methods can be executed by using the LibOdbc class

• For more information on the ODBC api go to Microsoft ODBC Documentation

Tested On

This package has been tested to be working on the following Database Servers

• Microsoft SQL Sever
• Oracle

Support for other Database Servers

• Although not tested, this plugin should work on any database that provides an ODBC Driver.
• For a comprehensive list of supported database servers checkout Drivers section of the official unixodbc site