Generic Scalar And List type SQL Select Function (VB.NET)

Here are a couple of utility functions I wrote to select basic types from a database, given that you have an open SqlConnection object. 

SqlSelect returns a single element of the specified type.

   1:      Public Function SqlSelect(Of T)(ByVal CN As SqlConnection, ByVal szSQL As String, ByRef szError As String) As T

   2:   

   3:          Dim T_value As T

   4:   

   5:          szError = String.Empty

   6:   

   7:          Try

   8:              Using sqlCmd As SqlCommand = New SqlCommand(szSQL, CN)

   9:                  T_value = CType(sqlCmd.ExecuteScalar(), T)

  10:              End Using

  11:          Catch ex As Exception

  12:              szError = ex.Message()

  13:          End Try

  14:   

  15:          Return T_value

  16:   

  17:      End Function

 

SqlSelectList returns a List of the specified type.

   1:      Public Function SqlSelectList(Of T)(ByVal CN As SqlConnection, ByVal szSQL As String, ByRef szError As String) As List(Of T)

   2:   

   3:          Dim T_LIST As New List(Of T)

   4:          szError = String.Empty

   5:   

   6:          Try

   7:              Using sqlCmd As SqlCommand = New SqlCommand(szSQL, CN)

   8:   

   9:                  Dim sqlReader As SqlDataReader = sqlCmd.ExecuteReader()

  10:                  If sqlReader.HasRows() = True Then

  11:                      Do While sqlReader.Read() = True

  12:                          T_LIST.Add(CType(sqlReader.GetValue(0), T))

  13:                      Loop

  14:                  End If

  15:                  sqlReader.Close()

  16:   

  17:              End Using

  18:          Catch ex As Exception

  19:              szError = ex.Message()

  20:          End Try

  21:   

  22:          Return T_LIST

  23:   

  24:      End Function

Now, with an open SqlConnection object CN, you can easily retrieve a scalar or list of scalar values like this:

   1:  szSQL = "SELECT COUNT(*) FROM [Users]"

   2:  Dim n As Integer = SqlSelect(Of Integer)(CN, szSQL, szError)

   3:   

   4:  szSQL = "SELECT name FROM sysobjects where type='U' and name <> 'sysdiagrams' order by name"

   5:  Dim TableList As List(Of String) = SqlSelectList(Of String)(CN, szSQL, szError)