轻松搞定数据访问层

' clsSQLBuilder

‘ By YuHonglai

‘ www.hahaIT.com

‘ [email protected]

' Note:提供重载方法以指明表名称，默认情况下，是传入参数 o 的类型＋"tbl_",此时类名称必须是 clsXXX 的形式.

' 如：

' dim Rooms as new clsRooms

' SQLBuilder.Add(Rooms)

' 此时程序将把 clsRooms 转换成 tbl_Rooms,以操作数据库表 tbl_Rooms

' 如果类名称和数据库表名称不具有上述对应关系，请使用 Add(o,"TableName")形式的方法，以显示指定要操作的数据库表的名称

Public Class SQLBuilder

    ' 当要生成的SQL语句的 where 条件语句很复杂时，用该常量作为 Select 方法中 FindCondition(HashTable)

    ' Key,例如：要生成 where Birth<' 2000-4-4 ' and Birth>' 1980-1-1 ' 的复杂条件时，用以下方法:

    ' Dim h as new HashTable

    ' h.Add(ComplexSQL,"_Birth<' 2000-4-4 ' and _Birth>' 1980-1-1 '")

    ' 注意，Birth是实体类的属性名称，前面必须有一个下划线 "_"

    ' 处理时，程序将用实际数据库字段名称代替相应的 _Birth

    Public Const ComplexSQL As String = "@ComplexSQL"

    ' 根具实体类生成相应的 Insert ...SQL 语句

    ' 如果与数据库表名称对应的属性时 关键字段而且是自动增加值时(在DB.XML文件中seed的值为 1 )

    ' 那么该属相将忽略,不会出现在返回的 Insert... SQL语句中

    Public Overloads Shared Function Add(ByVal o As Object) As String

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Return Add(o, typeString)

    End Function

    Public Overloads Shared Function Add(ByVal o As Object, ByVal TableName As String) As String

        Try

            Dim outSQL As String

            Dim tmpString As String

            outSQL = "insert into [" & TableName & "]("

            tmpString = ""

            Dim dsDB As New DataSet

            dsDB.ReadXml(clsPersistant.DBConfigPath)

            Dim row As Data.DataRow

            For Each row In dsDB.Tables(TableName).Rows

                If row.Item("seed") & "" = "0" Then

                    outSQL = outSQL & row.Item("dbname") & ","

                    tmpString = tmpString & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & ","

                End If

            Next

            outSQL = outSQL.Substring(0, outSQL.Length - 1)

            tmpString = tmpString.Substring(0, tmpString.Length - 1)

            outSQL = outSQL & ") values (" & tmpString & ")"

            For Each row In dsDB.Tables(TableName).Rows

                If row.Item("seed") & "" <> "1" Then

                    ' tmpString = o.GetType.InvokeMember(row.Item("name"), Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

                    tmpString = CallByName(o, CType(row.Item("name"), String).Trim, CallType.Get) & ""

                    If tmpString = "True" Then

                        tmpString = "1"

                    ElseIf tmpString = "False" Then

                        tmpString = "0"

                    End If

                    outSQL = outSQL.Replace("@" & row.Item("dbname"), tmpString)

                End If

            Next

            Return outSQL.Trim

        Catch ex As Exception

            Throw ex

        End Try

    End Function

    ' 如 Add 方法，关键字段不会更新

    ' 而且关键字段会作为 update....where .... 的 where 的条件出现

    Public Overloads Shared Function Update(ByVal o As Object) As String

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Return Update(o, typeString)

    End Function

    Public Overloads Shared Function Update(ByVal o As Object, ByVal TableName As String) As String

        Try

            Dim outString As String = ""

            Dim tmpString As String

            outString = "update [" & TableName & "] set "

            tmpString = ""

            Dim whereString As String = ""

            Dim dsDB As New DataSet

            dsDB.ReadXml(clsPersistant.DBConfigPath)

            Dim row As Data.DataRow

            For Each row In dsDB.Tables(TableName).Rows

                If row.Item("key") & "" = "1" Then

                    whereString = whereString & row.Item("dbname") & "=" & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & " and "

                Else

                    tmpString = tmpString & row.Item("dbname") & "=" & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & ","

                End If

            Next

            If whereString.Trim = "" Then

                Throw New Exception("必须指定一个以上的主键!")

            End If

            tmpString = tmpString.Substring(0, tmpString.Length - 1)

            whereString = whereString.Substring(0, whereString.Length - 4)

            outString = outString & tmpString & " where " & whereString

            For Each row In dsDB.Tables(TableName).Rows

                ' tmpString = o.GetType.InvokeMember(row.Item("name"), Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

                tmpString = CallByName(o, CType(row.Item("name"), String).Trim, CallType.Get) & ""

                If tmpString = "True" Then

                    tmpString = "1"

                ElseIf tmpString = "False" Then

                    tmpString = "0"

                End If

                outString = outString.Replace("@" & row.Item("dbname"), tmpString)

            Next

            Return outString.Trim

        Catch ex As Exception

            Throw ex

        End Try

    End Function

    ' 更具对象的关键属性(与数据库表的关键字段对应)删除指定的记录

    ' 对象的其他属性将被忽略

    Public Overloads Shared Function Delete(ByVal o As Object) As String

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Return Delete(o, typeString)

    End Function

    Public Overloads Shared Function Delete(ByVal o As Object, ByVal TableName As String) As String

        Try

            Dim outString As String = ""

            Dim tmpString As String

            outString = "delete from [" & TableName & "] where "

            Dim whereString As String = ""

            Dim dsDB As New DataSet

            dsDB.ReadXml(clsPersistant.DBConfigPath)

            Dim row As Data.DataRow

            For Each row In dsDB.Tables(TableName).Rows

                If row.Item("key") & "" = "1" Then

                    whereString = whereString & row.Item("dbname") & "=" & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & " and "

                End If

            Next

            If whereString.Trim = "" Then

                Throw New Exception("必须指定一个以上的主键!")

            End If

            whereString = whereString.Substring(0, whereString.Length - 4)

            outString = outString & tmpString & whereString

            For Each row In dsDB.Tables(TableName).Rows

                If row.Item("key") & "" = "1" Then

                    ' tmpString = o.GetType.InvokeMember(row.Item("name"), Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

                    tmpString = CallByName(o, CType(row.Item("name"), String).Trim, CallType.Get) & ""

                    outString = outString.Replace("@" & row.Item("dbname"), tmpString)

                End If

            Next

            Return outString.Trim

        Catch ex As Exception

            Throw ex

        End Try

    End Function

    ' 更具对象的关键属性(与数据库表的关键字段对应)判断该对象是否存在于数据库中

    ' 对象的其他属性将被忽略

    Public Overloads Shared Function Exists(ByVal o As Object) As String

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Return Exists(o, typeString)

    End Function

    Public Overloads Shared Function Exists(ByVal o As Object, ByVal TableName As String) As String

        Try

            Dim outString As String

            outString = "select count(*) from [" & TableName & "] where "

            Dim tmpString As String

            Dim whereString As String = ""

            Dim dsDB As New DataSet

            dsDB.ReadXml(clsPersistant.DBConfigPath)

            Dim row As Data.DataRow

            For Each row In dsDB.Tables(TableName).Rows

                If row.Item("key") & "" = "1" Then

                    whereString = whereString & row.Item("dbname") & "=" & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & " and "

                End If

            Next

            If whereString.Trim = "" Then

                Throw New Exception("必须指定一个以上的主键!")

            End If

            whereString = whereString.Substring(0, whereString.Length - 4)

            outString = outString & tmpString & whereString

            For Each row In dsDB.Tables(TableName).Rows

                If row.Item("key") & "" = "1" Then

                    ' tmpString = o.GetType.InvokeMember(row.Item("name"), Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

                    tmpString = CallByName(o, CType(row.Item("name"), String).Trim, CallType.Get) & ""

                    outString = outString.Replace("@" & row.Item("dbname"), tmpString)

                End If

            Next

            Return outString.Trim

        Catch ex As Exception

            Throw ex

        End Try

    End Function

    ' 生成 First SQL语句

    Public Overloads Shared Function First(ByVal o As Object) As String

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Return First(typeString)

    End Function

    Public Overloads Shared Function First(ByVal TableName As String) As String

        Dim MoudleSQL As String

        MoudleSQL = "select * from [%TableName%] where [%key%] in(select Min([%key%]) from [%TableName%])"

        Dim key As String

        Dim dsDB As New DataSet

        dsDB.ReadXml(clsPersistant.DBConfigPath)

        Dim row As Data.DataRow

        For Each row In dsDB.Tables(TableName).Rows

            If row.Item("key") = "1" Then

                key = CType(row.Item("dbname"), String).Trim

                Exit For

            End If

        Next

        MoudleSQL = MoudleSQL.Replace("%TableName%", TableName)

        MoudleSQL = MoudleSQL.Replace("%key%", key)

        Return MoudleSQL

    End Function

    Public Overloads Shared Function Last(ByVal o As Object) As String

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Return Last(typeString)

    End Function

    Public Overloads Shared Function Last(ByVal TableName As String) As String

        Dim MoudleSQL As String

        MoudleSQL = "select * from [%TableName%] where [%key%] in(select Max([%key%]) from [%TableName%])"

        Dim key As String

        Dim dsDB As New DataSet

        dsDB.ReadXml(clsPersistant.DBConfigPath)

        Dim row As Data.DataRow

        For Each row In dsDB.Tables(TableName).Rows

            If row.Item("key") = "1" Then

                key = CType(row.Item("dbname"), String).Trim

                Exit For

            End If

        Next

        MoudleSQL = MoudleSQL.Replace("%TableName%", TableName)

        MoudleSQL = MoudleSQL.Replace("%key%", key)

        Return MoudleSQL

    End Function

    Public Overloads Shared Function Previous(ByVal o As Object) As String

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Return Previous(o, typeString)

    End Function

    Public Overloads Shared Function Previous(ByVal o As Object, ByVal TableName As String) As String

        Dim MoudleSQL As String

        MoudleSQL = "select * from [%TableName%] where [%key%] in(select Max([%key%]) from [%TableName%] where [%key%]<%keyValue%)"

        Dim key As String

        Dim propertyName As String

        Dim propertyValue As String

        Dim dsDB As New DataSet

        dsDB.ReadXml(clsPersistant.DBConfigPath)

        Dim row As Data.DataRow

        For Each row In dsDB.Tables(TableName).Rows

            If row.Item("key") = "1" Then

                key = CType(row.Item("dbname"), String).Trim

                propertyName = CType(row.Item("name"), String).Trim

                Exit For

            End If

        Next

        ' propertyValue = o.GetType.InvokeMember(propertyName, Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

        propertyValue = CallByName(o, propertyName, CallType.Get) & ""

        MoudleSQL = MoudleSQL.Replace("%TableName%", TableName)

        MoudleSQL = MoudleSQL.Replace("%key%", key)

        MoudleSQL = MoudleSQL.Replace("%keyValue%", propertyValue)

        Return MoudleSQL

    End Function

    Public Overloads Shared Function [Next](ByVal o As Object) As String

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Return [Next](o, typeString)

    End Function

    Public Overloads Shared Function [Next](ByVal o As Object, ByVal TableName As String) As String

        Dim MoudleSQL As String

        MoudleSQL = "select * from [%TableName%] where [%key%] in(select Min([%key%]) from [%TableName%] where [%key%]>%keyValue%)"

        Dim key As String

        Dim propertyName As String

        Dim propertyValue As String

        Dim dsDB As New DataSet

        dsDB.ReadXml(clsPersistant.DBConfigPath)

        Dim row As Data.DataRow

        For Each row In dsDB.Tables(TableName).Rows

            If row.Item("key") = "1" Then

                key = CType(row.Item("dbname"), String).Trim

                propertyName = CType(row.Item("name"), String).Trim

                Exit For

            End If

        Next

        ' propertyValue = o.GetType.InvokeMember(propertyName, Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

        propertyValue = CallByName(o, propertyName, CallType.Get) & ""

        MoudleSQL = MoudleSQL.Replace("%TableName%", TableName)

        MoudleSQL = MoudleSQL.Replace("%key%", key)

        MoudleSQL = MoudleSQL.Replace("%keyValue%", propertyValue)

        Return MoudleSQL

    End Function

    ' 见 public const ComplexSQL 的说明

    Public Shared Function [Select](ByVal FindCondition As Hashtable, ByVal TableName As String) As String

        Dim outSQL As String

        If FindCondition.Contains(ComplexSQL) Then  ' 处理复杂类型的 Where 从句

            outSQL = "select * from [" & TableName & "] where " & FindCondition(ComplexSQL)

            Dim row As Data.DataRow

            Dim dsDB As New DataSet

            dsDB.ReadXml(clsPersistant.DBConfigPath)

            For Each row In dsDB.Tables(TableName).Rows

                outSQL = outSQL.Replace("_" & CType(row.Item("name"), String).Trim, "[" & CType(row.Item("dbname"), String).Trim & "]")

            Next

        Else

            outSQL = "select * from [" & TableName & "] where "

            Dim whereString As String = ""

            Dim eachKey As Object

            For Each eachKey In FindCondition.Keys

                whereString = whereString & CType(eachKey, String) & "=" & getS(getTypeByName(TableName, CType(eachKey, String))) & FindCondition(eachKey) & getS(getTypeByName(TableName, CType(eachKey, String))) & " and "

            Next

            If whereString.Length = 0 Then

                whereString = "0=0"

            Else

                whereString = whereString.Substring(0, whereString.Length - 5)

            End If

            outSQL = outSQL & whereString

        End If

        Return outSQL

    End Function

    ' 返回指定的字段(数据库表字段的名称)的数据类型名称(VB数据类型)

    Private Shared Function getTypeByName(ByVal TableName As String, ByVal n As String) As String

        Dim outStr As String

        Dim dsDB As New Data.DataSet

        dsDB.ReadXml(clsPersistant.DBConfigPath)

        Dim eachRow As DataRow

        For Each eachRow In dsDB.Tables(TableName).Rows

            If CType(eachRow.Item("dbname"), String).Trim.ToLower = n.Trim.ToLower Then

                outStr = CType(eachRow.Item("type"), String).Trim.ToLower

                Exit For

            End If

        Next

        Return outStr

    End Function

    ' 根具数据类型名称，返回空或' SQL语句中数字和字符型是否被‘括起来

    Private Shared Function getS(ByVal t As String) As String

        Dim outString As String

        t = t.ToLower.Trim

        If t = "single" Or t = "int16" Or t = "int32" Or t = "int64" Or t = "double" Or t = "byte" Then

            outString = ""

            Return outString

        ElseIf t = "date" Or t = "string" Then

            outString = "'"

            Return outString

        End If

    End Function

End Class

' clsDataAccessOper 该类是所有数据访问类的父类

' by YuJun

‘ www.hahaIT.com

‘ [email protected]

Public Class clsDataAccessOper

    ' 当Update,Delete,Add方法操作失败返回 False 时，记录出错的信息

    Public Shared ModifyErrorString As String

    Private Shared Keys As New Hashtable

    ' 数据库连接字符串

    Public Shared Property ConnectionString() As String

        Get

            Return SqlHelper.cnnString.Trim

        End Get

        Set(ByVal Value As String)

            SqlHelper.cnnString = Value.Trim

        End Set

    End Property

    ' Update 不更新主键，包括联合主键

    Public Shared Function Update(ByVal o As Object) As Boolean

        ModifyErrorString = ""

        Try

            If CType(SqlHelper.ExecuteNonQuery(SqlHelper.cnnString, CommandType.Text, SQLBuilder.Exists(o)), Int64) = 0 Then

                Throw New Exception("该记录不存在!")

            End If

        Catch ex As Exception

            Throw ex

        End Try

        Try

            SqlHelper.ExecuteNonQuery(SqlHelper.cnnString, CommandType.Text, SQLBuilder.Update(o))

        Catch ex As Exception

            ModifyErrorString = ex.Message

            Return False

        End Try

        Return True

    End Function

    ' Delete 将忽略

    Public Shared Function Delete(ByVal o As Object) As Boolean

        ModifyErrorString = ""

        Try

            SqlHelper.ExecuteNonQuery(SqlHelper.cnnString, CommandType.Text, SQLBuilder.Delete(o))

        Catch ex As Exception

            ModifyErrorString = ex.Message

            Return False

        End Try

        Return True

    End Function

    ' Add 方法将忽略自动增加值的主键

    Public Shared Function Add(ByVal o As Object) As Boolean

        ModifyErrorString = ""

        Try

            SqlHelper.ExecuteNonQuery(SqlHelper.cnnString, CommandType.Text, SQLBuilder.Add(o))

        Catch ex As Exception

            ModifyErrorString = ex.Message

            Return False

        End Try

        Return True

    End Function

    ' 通用数据库查询方法

    ' 重载方法用于明确指定要操作的数据库表名称

    ' 否则会以 ReturnType 的类型描述得到要操作的数据库表的名称 eg: ReturnType="clsRooms" ,得道 TableName="tbl_Rooms"

    ' 该查询方法将查询条件添加到 Keys(HashTable) 中，然后调用 Select 方法返回 对象的集合

    ' 当Keys包含特殊键时，将要处理的是复杂类型的查询,见 SQLBuilder 的 ComplexSQL 说明

    ' 该方法可以拓展数据访问类的固定查询方法

    Public Overloads Shared Function [Select](ByVal ReturnType As Type) As ArrayList

        Dim tableName As String

        tableName = ReturnType.Name

        Dim i As Int16

        i = tableName.IndexOf("cls") + 3

        tableName = "tbl_" & tableName.Substring(i, tableName.Length - i)

        Return [Select](ReturnType, tableName)

    End Function

    Public Overloads Shared Function [Select](ByVal ReturnType As Type, ByVal TableName As String) As ArrayList

        Dim alOut As New ArrayList

        Dim dsDB As New Data.DataSet

        dsDB.ReadXml(clsPersistant.DBConfigPath)

        Dim xxxH As New Hashtable

        Dim eachRow As Data.DataRow

        For Each eachRow In dsDB.Tables(TableName).Rows

            If Keys.Contains(CType(eachRow.Item("name"), String).ToLower.Trim) Then

                xxxH.Add(CType(eachRow.Item("dbname"), String).ToLower.Trim, Keys(CType(eachRow.Item("name"), String).Trim.ToLower))

            End If

        Next

        ' 检查 Keys 的合法性

        Dim dsSelect As New Data.DataSet

        If Keys.Count <> xxxH.Count Then

            Keys.Clear()

            Dim InvalidField As New Exception("没有您设置的字段:")

            Throw InvalidField

        Else

            Keys.Clear()

            Try

                dsSelect = SqlHelper.ExecuteDataset(SqlHelper.cnnString, CommandType.Text, SQLBuilder.Select(xxxH, TableName))

            Catch ex As Exception

                Throw ex

            End Try

        End If

        Dim eachSelect As Data.DataRow

        Dim fieldName As String

        Dim DBfieldName As String

        For Each eachSelect In dsSelect.Tables(0).Rows

            Dim newObject As Object = System.Activator.CreateInstance(ReturnType)

            For Each eachRow In dsDB.Tables(TableName).Rows

                fieldName = CType(eachRow.Item("name"), String).Trim

                DBfieldName = CType(eachRow.Item("dbname"), String).Trim

                CallByName(newObject, fieldName, CallType.Set, CType(eachSelect.Item(DBfieldName), String).Trim)

            Next

            alOut.Add(newObject)

            newObject = Nothing

        Next

        Return alOut

    End Function

    Public Shared WriteOnly Property SelectKeys(ByVal KeyName As String)

        Set(ByVal Value As Object)

            Keys.Add(KeyName.Trim.ToLower, Value)

        End Set

    End Property

    ' 下面4个方法用来移动记录

    ' 移动记录安主键的大小顺序移动，只能对有且仅有一个主键的表操作

    ' 对于组合主键，返回 Nothing

    ' 当记录移动到头或末尾时 返回 Noting,当表为空时，First,Last 均返回Nothing

    Public Shared Function First(ByVal o As Object) As Object

        Return Move("first", o)

    End Function

    Public Shared Function Last(ByVal o As Object) As Object

        Return Move("last", o)

    End Function

    Public Shared Function Previous(ByVal o As Object) As Object

        Return Move("previous", o)

    End Function

    Public Shared Function [Next](ByVal o As Object) As Object

        Return Move("next", o)

    End Function

    ' 返回一个表的主键的数量，keyName,keyDBName 记录的是最后一个主键

    Private Shared Function getKey(ByRef keyName As String, ByRef keyDBName As String, ByVal TableName As String) As Int16

        Dim keyNum As Int16 = 0

        Dim dsDB As New DataSet

        dsDB.ReadXml(clsPersistant.DBConfigPath)

        Dim row As Data.DataRow

        For Each row In dsDB.Tables(TableName).Rows

            If row.Item("key") = "1" Then

                keyNum = keyNum + 1

                keyName = CType(row.Item("name"), String).Trim

                keyDBName = CType(row.Item("dbname"), String).Trim

                Exit For

            End If

        Next

        Return keyNum

    End Function

    ' 为 First,Previous,Next,Last 提供通用函数

    Private Shared Function Move(ByVal Type As String, ByVal o As Object) As Object

        Dim moveSQL As String

        Select Case Type.Trim.ToLower

            Case "first"

                moveSQL = SQLBuilder.First(o)

            Case "last"

                moveSQL = SQLBuilder.Last(o)

            Case "previous"

                moveSQL = SQLBuilder.Previous(o)

            Case "next"

                moveSQL = SQLBuilder.Next(o)

        End Select

        Dim typeString As String = o.GetType.ToString

        Dim i As Int16

        i = typeString.IndexOf("cls") + 3

        typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

        Dim TableName As String = typeString

        Dim keyName As String

        Dim keyDBName As String

        Dim tmpString As String

        If getKey(keyName, keyDBName, TableName) = 1 Then

            Keys.Clear()

            Dim ds As New Data.DataSet

            ds = SqlHelper.ExecuteDataset(SqlHelper.cnnString, CommandType.Text, moveSQL)

            If ds.Tables(0).Rows.Count = 0 Then

                Return Nothing

            Else

                tmpString = CType(ds.Tables(0).Rows(0).Item(keyDBName), String).Trim

                Keys.Add(keyName.Trim.ToLower, tmpString)

                Dim al As New ArrayList

                al = [Select](o.GetType)

                If al.Count = 1 Then

                    Return al.Item(0)

                Else

                    Return Nothing

                End If

            End If

        Else

            Return Nothing

        End If

    End Function

End Class