C# Code Snippet - Get Data From SqlDataReader using open connection

C# Code Snippet - Get Data From SqlDataReader using open connection

This .Net C# 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.

public System.Data.SqlClient.SqlDataReader GetSqlDataReader(
                ref System.Data.SqlClient.SqlConnection _SqlConnection, 
                string _SQL)
{
    // Set temporary variable to create data reader
    System.Data.SqlClient.SqlDataReader _SqlDataReader = null;

    // lets run the given SQL statement and create SqlDataReader
    try
    {
        // Pass the connection to a command object
        System.Data.SqlClient.SqlCommand _SqlCommand =
                new 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 null;
    }

    // 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 = new 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 != null && _SqlConnection.State == ConnectionState.Open)
{
    // Lets call above function to create a new SqlDataReader
	// using open database connection and SQL statement
    System.Data.SqlClient.SqlDataReader _SqlDataReader = GetSqlDataReader(
        // Pass open database connection to function
        ref _SqlConnection,
        // Pass SQL statement to create SqlDataReader
        "SELECT NAME, PRICE, COST FROM INVENTORY");

    // Check we have data
    if (_SqlDataReader != null && _SqlDataReader.HasRows)
    {
        Console.WriteLine(_SqlDataReader["NAME"].ToString());
    }
    
    // close sql reader
    if (_SqlDataReader != null)
    {
        _SqlDataReader.Close();
        _SqlDataReader.Dispose();
    }    

    // close database connection
    _SqlConnection.Close();
}

C# Keywords Used:

• SqlDataReader
• SqlConnection
• ConnectionString
• SqlCommand
• ExecuteReader
• Exception

Code Snippet Information:

• Applies To: .Net, C#, CLI, SQL, SQL Server, SQL Client, Connection String, Database Connection, SQL Data Reader
• Programming Language : C# (C-Sharp)

External Resources:

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

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