Visual Basic Code Snippet - Get First Row As Object Array From SqlDataReader

Visual Basic Code Snippet - Get First Row As Object Array From SqlDataReader

This .Net Visual Basic code snippet execute a SQL statement using open database connection and return all the columns data in SqlDataReader for first row. Additional rows are ignored. This function is useful for query for one data record row, after querying function will convert data row into dictionary object array and close SqlDataReader. Conversion of SqlDataReader into dictionary object array and closing SqlDataReader allows to create multiple object arrays without having to worry about opening more than one SqlDataReader for SQL Server. 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 Function GetSqlDataReaderFirstRow(ByRef _SqlConnection As System.Data.SqlClient.SqlConnection, ByVal _SQL As String) As Dictionary(Of String, Object)
    ' temporary dictionary object array to hold SqlDataReader first row
    Dim _FirstRow As New Dictionary(Of String, Object)()

    ' Set temporary variable to create data reader
    Dim _SqlDataReader As System.Data.SqlClient.SqlDataReader = Nothing

    ' lets run the given SQL statement and get the data to SqlDataReader
    Try
        ' Pass the connection to a command object
        Dim _SqlCommand As New System.Data.SqlClient.SqlCommand(_SQL, _SqlConnection)

        ' get query results
        _SqlDataReader = _SqlCommand.ExecuteReader()

    Catch _Exception As 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 Nothing
    End Try

    ' SQL successfully executed, lets return the SqlDataReader First Data Row
    If _SqlDataReader IsNot Nothing AndAlso _SqlDataReader.HasRows AndAlso _SqlDataReader.Read() Then
        ' put the first data row in a temporary object array before close SqlDataReader
        For _Column As Integer = 0 To _SqlDataReader.FieldCount - 1
            Try
                ' Add each colum to dictionary
                _FirstRow.Add(_SqlDataReader.GetName(_Column), _SqlDataReader(_Column))
            Catch
            End Try
        Next _Column

        ' close SqlDataReader
        _SqlDataReader.Close()
        _SqlDataReader.Dispose()

        Return _FirstRow
    Else
        If _SqlDataReader IsNot Nothing Then
            ' close SqlDataReader
            _SqlDataReader.Close()
            _SqlDataReader.Dispose()
        End If

        ' no data found, return null
        Return Nothing
    End If
End Function

Here is a simple example showing how to use above function (GetSqlDataReaderFirstRow) to connect to SQL database and get Dictionary Object Array for given SQL statement.

' set temporary variable for database connection
Dim _SqlConnection As 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 As Exception
    ' Error occurred while trying to connect to database
    Console.WriteLine(_Exception.Message)
End Try
            
' Check for valid open database connection before query database
If _SqlConnection IsNot Nothing AndAlso _SqlConnection.State = ConnectionState.Open Then
    ' 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
    Dim _SqlDataReaderFirstRow As Dictionary(Of String, Object) = GetSqlDataReaderFirstRow(_SqlConnection, "SELECT NAME, PRICE, COST FROM INVENTORY")

    ' Check we have data
    If _SqlDataReaderFirstRow IsNot Nothing AndAlso _SqlDataReaderFirstRow.Count > 0 Then
        'Console.WriteLine(_SqlDataReaderFirstRow("NAME").ToString());
    End If

    ' close database connection
    _SqlConnection.Close();
End If

VB Keywords Used:

• SqlDataReader
• SqlConnection
• ConnectionString
• SqlCommand
• ExecuteReader
• Exception
• Dictionary
• Try, Catch
• For, Next
• GetName

Code Snippet Information:

• Applies To: .Net, VB, Visual Basic, CLI, SQL, SqlDataReader, SQL Server, SQL Client, Database Connection, SQL Data Reader, Object Array
• Programming Language : VB (Visual Basic)

External Resources:

• SqlDataReader Class
• SqlConnection Class
• SqlConnection.ConnectionString Property
• SqlCommand Class
• SqlCommand.ExecuteReader Method
• Exception Class
• Dictionary(TKey, TValue) Class
• Loop Structures

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