Imports System

Imports System.Data

Imports System.Data.SqlClient

Imports System.Data.SqlTypes

Imports Microsoft.SqlServer.Server

Imports System.Runtime.InteropServices





Partial Public Class UserDefinedFunctions

    <Microsoft.SqlServer.Server.SqlFunction()> _

    Public Shared Function EVAL(ByVal InputExpression As SqlString) As SqlDecimal

        Return Evaluate(InputExpression)

    End Function



    Private Shared Function Evaluate(ByVal expression As SqlString) As SqlDecimal

        Dim expressionStr As String = expression.ToString()

        Dim loDataTable = New DataTable()

        Dim loDataColumn = New DataColumn("Eval", GetType(Double), expressionStr)

        loDataTable.Columns.Add(loDataColumn)

        loDataTable.Rows.Add(0)

        Return ParseDecimal(loDataTable.Rows(0)("Eval").ToString(), 0)

    End Function



    Public Shared Function ParseDecimal(ByVal InputStr As String, Optional ByVal ReturnIfFail As Decimal = 0) As Decimal

        Dim ParseOutput As Decimal = 0

        If Decimal.TryParse(InputStr, ParseOutput) = False Then

            Return ReturnIfFail

        Else

            Return ParseOutput

        End If

    End Function

End Class