SqlParameter的用法

            Dim sql As StringBuilder = New StringBuilder()
            sql.Append("")
            sql.Append("SELECT * FROM test")
            sql.Append(" WHERE  a= @p1 ")           

            Dim command As SqlCommand    =    dac.CreateCommand(sql.ToString())  'dac为自己写的类
            Dim param As SqlParameter = New SqlParameter()
            param .ParameterName = "@p1"
            param .SqlDbType = SqlDbType.NVarChar
            param .Value = b       'b为该函数的参数(ByVal b as String)
            command .Parameters.Add(param)
            Dim reader As SqlDataReader = command.ExecuteReader()