C++/CLI Code Snippet - Get Data From SqlDataReader using open connection

C++/CLI Code Snippet - Get Data From SqlDataReader using open connection

This .Net C++/CLI code snippet connect connects to SQL server and executes SQL statement and return SqlDataReader. To use this function simply provide open database connection and SQL statement. This function uses SqlClient name space to get data using SqlDataReader. Modify the exception handling section for your project requirements.

System::Data::SqlClient::SqlDataReader ^GetSqlDataReader2(System::Data::SqlClient::SqlConnection ^%_SqlConnection, System::String ^_SQL)
{
    // Set temporary variable to create data reader
    System::Data::SqlClient::SqlDataReader ^_SqlDataReader = nullptr;

    // lets run the given SQL statement and create SqlDataReader
    try
    {
        // Pass the connection to a command object
        System::Data::SqlClient::SqlCommand ^_SqlCommand = gcnew System::Data::SqlClient::SqlCommand(_SQL, _SqlConnection);

        // get query results
        _SqlDataReader = _SqlCommand->ExecuteReader();
    }
    catch (Exception ^_Exception)
    {
        // Error occurred while trying to execute reader
        // send error message to console (change below line to customize error handling)
        Console::WriteLine(_Exception->Message);

        // failed SQL execution, lets return null
        return nullptr;
    }

    // SQL successfully executed, lets return the SqlDataReader
    return _SqlDataReader;
}

Here is a simple example showing how to use above function (GetSqlDataReader) to connect to SQL database and get SqlDataReader for given SQL statement.

// set temporary variable for database connection
System::Data::SqlClient::SqlConnection ^_SqlConnection = gcnew System::Data::SqlClient::SqlConnection();

// assign database connection string
_SqlConnection->ConnectionString = "Server=SERVERADDRESS;Database=DATABASENAME;Uid=USERID;Pwd=PASSWORD;";

// Connect to database
try
{
    _SqlConnection->Open();
}
catch (Exception ^_Exception)
{
    // Error occurred while trying to connect to database
    Console::WriteLine(_Exception->Message);
}


// Check for valid open database connection before query database
if (_SqlConnection != nullptr && _SqlConnection->State == ConnectionState::Open)
{
    // Lets call above function to create a new SqlDataReader
    // using open database connection and SQL statement
        // Pass open database connection to function
        // Pass SQL statement to create SqlDataReader
    System::Data::SqlClient::SqlDataReader ^_SqlDataReader = GetSqlDataReader2(_SqlConnection, "SELECT NAME, PRICE, COST FROM INVENTORY");

    // Check we have data
    if (_SqlDataReader != nullptr && _SqlDataReader->HasRows)
    {
        // We have data in SqlDataReader, lets loop through and display the data
        while (_SqlDataReader->Read())
        {
            Console::WriteLine(_SqlDataReader["NAME"]->ToString());
        }

        // Close SqlDataReader
        _SqlDataReader->Close();
        delete _SqlDataReader;
    }

    // close database connection
    _SqlConnection->Close();
}

C++/CLI Keywords Used:

• SqlDataReader
• SqlConnection
• ConnectionString
• SqlCommand
• ExecuteReader
• Exception
• nullptr
• Close
• delete
• Console
• WriteLine

Code Snippet Information:

• Applies To: .Net, C++, CLI, SqlDataReader, SQL, SQL Server, SQL Client, Connection String, Database Connection, SQL Data Reader
• Programming Language : C++/CLI

External Resources:

• SqlDataReader Class
• SqlConnection Class
• SqlConnection.ConnectionString Property
• SqlCommand Class
• SqlCommand.ExecuteReader Method
• Exception Class

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