Visual Basic Code Snippet - Get Scalar using open connection

Visual Basic Code Snippet - Get Scalar using open connection

This .Net Visual Basic code snippet connects to SQL server and executes SQL statement and returns the first column of the first row in the result set returned by the query as a object. Additional columns or rows are ignored. To use this function simply provide open database connection and SQL statement. This function uses SqlClient name space to get data using SqlCommand. Modify the exception handling section to as your project requirements.

Public Function ExecuteScalar(ByRef _SqlConnection As System.Data.SqlClient.SqlConnection, ByVal _SQL As String) As Object
    Dim _SqlRetVal As Object = Nothing

    Try
        ' Executes the query, and returns the first column of the first row in the result 
        ' set returned by the query. Additional columns or rows are ignored.
        Dim _SqlCommand As New System.Data.SqlClient.SqlCommand(_SQL, _SqlConnection)

        _SqlRetVal = _SqlCommand.ExecuteScalar()

        ' Dispose command
        _SqlCommand.Dispose()
        _SqlCommand = Nothing
    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)

        Return Nothing
    End Try

    Return _SqlRetVal
End Function

Here is a simple example showing how to use above function (ExecuteScalar) to connect to SQL database and get first column of the first row in the result set returned by the query as a object.

' 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 execute scalar
    ' using open database connection and SQL statement
        ' Pass open database connection to function
        ' Pass SQL statement to create SqlDataReader
    Dim _object As Object = ExecuteScalar(_SqlConnection, "SELECT name FROM sampletable")

    ' Check we have data
    If _object IsNot Nothing Then
        Console.WriteLine(_object.ToString())
    End If

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

VB Keywords Used:

• ExecuteScalar
• SqlConnection
• ConnectionString
• SqlCommand
• Exception

Code Snippet Information:

• Applies To: .Net, VB, Visual Basic, CLI, SQL, SqlCommand, ExecuteScalar, SQL Server, SQL Client, Connection String, Database Connection, SQL Data Reader
• Programming Language : Visual Basic (VB)

External Resources:

• SqlCommand.ExecuteScalar Method
• SqlConnection Class
• SqlConnection.ConnectionString Property
• SqlCommand Class
• Exception Class

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