是什么原因导致我的SQL Server权限从一个存储过程的一次执行更改为下一次执行

我使用的存储过程在第一次执行时运行，不会抱怨权限问题。存储过程只设置了一个UID/PWD（没有用于授予不同权限级别的不同UID/PW集）。单个对提供了对所有内容的权限。

我调用存储过程的代码是：

DataTable dtPriceComplianceResults 
SQLDBHelper.ExecuteSQLReturnDataTable(PriceComplianceConstsAndUtils.SUMMARY_STOREDPROC, CommandType.StoredProcedure,
        new SqlParameter()
        {
            ParameterName = "@BegDate",
            SqlDbType = SqlDbType.VarChar, 
            Value = _begDateStr
        },
        new SqlParameter()
        {
            ParameterName = "@EndDate",
            SqlDbType = SqlDbType.VarChar,
            Value = _endDateStr
        },
        new SqlParameter()
        {
            ParameterName = "@Member",
            SqlDbType = SqlDbType.VarChar,
            Value = _member
        },
        new SqlParameter()
        {
            ParameterName = "@Unit",
            SqlDbType = SqlDbType.VarChar,
            Value = _unit
        });
        public static DataTable ExecuteSQLReturnDataTable(string sql, CommandType cmdType, params SqlParameter[] parameters)
        {
            using (DataSet ds = new DataSet())
            using (SqlConnection connStr = new SqlConnection(PriceComplianceConstsAndUtils.CPSConnStr))
            using (SqlCommand cmd = new SqlCommand(sql, connStr))
            {
                cmd.CommandType = cmdType;
                cmd.CommandTimeout = EXTENDED_TIMEOUT;
                foreach (var item in parameters)
                {
                    cmd.Parameters.Add(item);
                }
                try
                {
                    cmd.Connection.Open();
                    new SqlDataAdapter(cmd).Fill(ds);
                }
                catch (SqlException sqlex)
                {
                    for (int i = 0; i < sqlex.Errors.Count; i++)
                    {
                        var sqlexDetail = String.Format("From ExecuteSQLReturnDataTable(), SQL Exception #{0}{1}Source: {2}{1}Number: {3}{1}State: {4}{1}Class: {5}{1}Server: {6}{1}Message: {7}{1}Procedure: {8}{1}LineNumber: {9}",
                            i + 1, // Some users would get the fantods if they saw #0
                            Environment.NewLine,
                            sqlex.Errors[i].Source,
                            sqlex.Errors[i].Number,
                            sqlex.Errors[i].State,
                            sqlex.Errors[i].Class,
                            sqlex.Errors[i].Server,
                            sqlex.Errors[i].Message,
                            sqlex.Errors[i].Procedure,
                            sqlex.Errors[i].LineNumber);
                        MessageBox.Show(sqlexDetail);
                    }
                }
                catch (Exception ex)
                {
                    String exDetail = String.Format(PriceComplianceConstsAndUtils.ExceptionFormatString, ex.Message, Environment.NewLine, ex.Source, ex.StackTrace);
                    MessageBox.Show(exDetail);
                }
                return ds.Tables[0];
            }
        }

这是存储过程的第一部分：

ALTER procedure [dbo].[sp_duckbilled_platypus]
    @BegDate varchar(10),
    @EndDate varchar(10),
    @Member varchar(max),
    @Unit varchar(max)
AS
    drop table zDistDBPExceptions 
    select (ph.memberno), TotalDesExceptions=1
    into zDistDBPExceptions
    from    priceexceptionshistory ph
    inner join MasterUnits MU on ph.Unit=MU.Unit
    Inner Join Members M on ph.memberno = M.MemberNo
    where   ph.memberNo not in ('04501','04503')    --,'111','B140') 
    and ph.memberno in (select [value] from dbo.split(@member,','))
    and  ph.Unit in (select [value] from dbo.Split(@Unit,','))
    and     invoicedate between @BegDate and @EndDate
    and     filtered=0
    and     abs(contractprice) = 0
    and     abs(ph.pricepush) = 0
    and     bidprice > 0
    and     abs(MU.TruTrack) = 1 
    and     abs(ph.pricesheet) = 1
    drop table zContractDBPExceptions
    select (ph.memberno), TotalContractExceptions=1
    into zContractDBPExceptions
    from    priceexceptionshistory ph
        inner join MasterUnits MU on ph.Unit=MU.Unit
        Inner Join Members M on ph.memberno = M.MemberNo
    where ph.memberNo not in ('04501','04503')  --,'111','B140') 
        and     ph.memberno in (select [value] from dbo.split(@member,','))
        and     ph.Unit in (select [value] from dbo.Split(@Unit,','))
        and     invoicedate between @BegDate and @EndDate
        and     filtered=0
        and     abs(contractprice) = 1
        and     abs(ph.pricepush) = 1
        and     bidprice > 0
        and     abs(MU.TruTrack) = 1 
    drop table zDBPExceptions
    select (ph.memberno), TotalPriceSheetExceptions=1--, invoicedate
    into zDBPExceptions
    from    priceexceptionshistory ph
    inner join MasterUnits MU on ph.Unit=MU.Unit
        Inner Join Members M on ph.memberno = M.MemberNo
    where   ph.memberNo not in ('04501','04503')    --,'111','B140')
    and ph.memberno in (select [value] from dbo.split(@member,','))
    and  ph.Unit in (select [value] from dbo.Split(@Unit,','))
    and     invoicedate between @BegDate and @EndDate
    and     filtered=0
    and     abs(contractprice) = 0
    and     abs(ph.pricepush) = 1
    and     bidprice > 0
    and     abs(MU.TruTrack) = 1 
    drop table zSumtDBPExceptions
    select (ph.memberno), TotalSumExceptions=1
    into zSumtDBPExceptions
    from    priceexceptionshistory ph
    inner join MasterUnits MU on ph.Unit=MU.Unit
    Inner Join Members M on ph.memberno = M.MemberNo
    where   ph.memberNo not in ('04501','04503')    --,'111','B140') 
    and ph.memberno in (select [value] from dbo.split(@member,','))
    and  ph.Unit in (select [value] from dbo.Split(@Unit,','))
    and     invoicedate between @BegDate and @EndDate
    and     filtered=0
    and     bidprice > 0
    and     abs(MU.TruTrack) = 1 
    and     abs(ph.pricesheet) = 1
    --this gets all invoice data
    --insert into PriceExceptionsHistory
    -- *** zContractDBPBase *** 
    drop table zContractDBPBase
    . . .

发生的一件非常奇怪的事情（ISTM）是，昨天存储过程根本无法运行，告诉我要么被丢弃的表（所有表都被丢弃在存储过程中，每个表都依次列出）不存在，要么我没有访问它们的权限。它们确实都存在。因此，权限似乎是个问题。

然而，今天上午，在没有更改代码或数据库的情况下，存储过程最初运行时没有抱怨权限问题（仅是第一次）。

然而，在第二次执行时，它抱怨我没有zContractDBPBase表的权限。我想我现在有权删除前四个，但没有这个。。。？！？

IOW，我得到的错误消息（在"Query completed with errors"之后）现在是：

消息3701，级别11，状态5，过程sp_zDBP_pella，第80行
无法删除表"zContractDBPBase"，因为它不存在或您没有权限。

而以前是相同的消息，但对于所有丢弃的表，而不仅仅是一个。

那么，为什么权限是可变的呢？我刷新了表的列表，仍然可以看到我显然没有权限访问的表（"zContractDBPBase"）；在Visual Studio IDE中的服务器资源管理器和LINQPad中刷新时都可以看到它。

我需要做什么（除了更改存储过程本身，这超出了我的职责和专业知识范围）才能让存储过程允许"我"删除表？