C# Code Snippet - Get DataTable using open connection

C# Code Snippet - Get DataTable using open connection

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

public DataTable GetDataTable(
        ref System.Data.SqlClient.SqlConnection _SqlConnection,
        string _SQL)
{
    // Pass the connection to a command object
    System.Data.SqlClient.SqlCommand _SqlCommand =
                    new System.Data.SqlClient.SqlCommand(_SQL, _SqlConnection);
    System.Data.SqlClient.SqlDataAdapter _SqlDataAdapter 
                    = new System.Data.SqlClient.SqlDataAdapter();
    _SqlDataAdapter.SelectCommand = _SqlCommand;

    DataTable _DataTable = new DataTable();
    _DataTable.Locale = System.Globalization.CultureInfo.InvariantCulture;

    // Adds or refreshes rows in the DataSet to match those in the data source
    try
    {
        _SqlDataAdapter.Fill(_DataTable);
    }
    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);

        return null;
    }

    return _DataTable;
}

Here is a simple example showing how to use above function (GetDataTable) to connect to SQL database and get DataTable 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
    DataTable _DataTable = GetDataTable(
        // Pass open database connection to function
        ref _SqlConnection,
        // Pass SQL statement to create SqlDataReader
        "SELECT * FROM SampleTable");

    // Check we have data
    if (_DataTable != null)
    {
        dataGridView1.DataSource = _DataTable;
    }

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

C# Keywords Used:

• DataTable
• SqlDataAdapter
• SqlConnection
• ConnectionString
• SqlCommand
• Exception

Code Snippet Information:

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

External Resources:

• DataTable Class
• SqlDataAdapter Class
• SqlConnection Class
• SqlConnection.ConnectionString Property
• SqlCommand Class
• Exception Class

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