SQL2005支持在SQL SERVER里部署.net应用程序了，那么以前一直写在.net里的一些运算如加密等已经完全可以移到sql里来进行了，而不需要再从程序中运算了，使数据库可以和程序相对独立开来，方便了不少。
    前阵子，需要给数据加密，所以写了个3DES加密函数部署到SQL2005中，当然,现在秘钥也作为一个表存在在数据库中,至于这个密钥,以后可以考虑用usb-key使用rsa加密或者别的方式进行加密,以保证数据安全。现在先说怎么实现部署到sqlserver中的加密函数吧。
    新建一个项目。VB中的database-->SQL Server Project，我新建了以后叫做DESCryptoService的项目，之后，会让你添加数据库引用，选择你要部署到的数据库。
写入如下代码，就OK了

Imports System
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.SqlTypes
Imports Microsoft.SqlServer.Server
Imports System.IO
Imports System.Xml
Imports System.Text
Imports System.Security.Cryptography

Partial Public Class EncryptToBase64DecryptFromBase64Class EncryptToBase64DecryptFromBase64

    <Microsoft.SqlServer.Server.SqlFunction()> _
    Public Shared Function EncryptToBase64String()Function EncryptToBase64String(ByVal stringToEncryptsql As SqlString, ByVal SEncryptionKeysql As SqlString) As SqlString
        Dim stringToEncrypt As String = CType(stringToEncryptsql, String)
        Dim SEncryptionKey As String = CType(SEncryptionKeysql, String)
        Dim IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}
        Dim key() As Byte = {}
        Try
            key = System.Text.Encoding.UTF8.GetBytes(Left(SEncryptionKey, 8))
            Dim des As New DESCryptoServiceProvider()
            Dim inputByteArray() As Byte = Encoding.UTF8.GetBytes(stringToEncrypt)
            Dim ms As New MemoryStream()
            Dim cs As New CryptoStream(ms, des.CreateEncryptor(key, IV), CryptoStreamMode.Write)
            cs.Write(inputByteArray, 0, inputByteArray.Length)
            cs.FlushFinalBlock()
            Return Convert.ToBase64String(ms.ToArray())
        Catch e As Exception
            Return CType(e.Message, SqlString)
        End Try
    End Function

    <Microsoft.SqlServer.Server.SqlFunction()> _
        Public Shared Function DecryptFromBase64String()Function DecryptFromBase64String(ByVal stringToDecryptsql As SqlString, ByVal sEncryptionKeysql As SqlString) As SqlString
        Dim stringToDecrypt As String = CType(stringToDecryptsql, String)
        Dim sEncryptionKey As String = CType(sEncryptionKeysql, String)
        Dim inputByteArray(stringToDecrypt.Length) As Byte
        Dim IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}
        Dim key() As Byte = {}
        Try
            key = System.Text.Encoding.UTF8.GetBytes(Left(sEncryptionKey, 8))
            Dim des As New DESCryptoServiceProvider()
            inputByteArray = Convert.FromBase64String(stringToDecrypt)
            Dim ms As New MemoryStream()
            Dim cs As New CryptoStream(ms, des.CreateDecryptor(key, IV), CryptoStreamMode.Write)
            cs.Write(inputByteArray, 0, inputByteArray.Length)
            cs.FlushFinalBlock()
            Dim encoding As System.Text.Encoding = System.Text.Encoding.UTF8
            Return encoding.GetString(ms.ToArray())
        Catch e As Exception
            Return CType(e.Message, SqlString)
        End Try
    End Function

End Class

完成之后选择生成，部署即可

至于测试，是否可用，打开查询分析器，执行下面语句，
SELECT dbo.DecryptFromBase64String(dbo.EncryptToBase64String('123456','12345678'),'12345678')
如果出现正确的值：123456,说明成功了