如何在存储过程中循环访问表？

这个问题是从this one.

我有两个表需要查询并从中收集一些计算所得的总和；我需要一个基于单位的结果集——每个单位一行，并将它们的计算数据折叠到该行中。

这两个表包含以下相关成员：

客户类别日志:

Unit        varchar(25)
MemberNo    varchar(10)
Category    varchar(50)
Subcategory varchar(50)
BeginDate   Datetime
EndDate     Datetime

报告每月销售额:

Unit (VarChar)
MemberNo (VarChar)
MonthlySales (Money)
CYear (Int)
Cmonth (Int)

对于每个单元（两个表中都有许多行，每个单元对应一个 MemberNo，但在结果集中包含一行），我需要填充四列：New、Assumed、Existing 和 Organic。这些值是基于属于相应“子类别”字段的单元所有成员的总和。 CustomerCategoryLog 表的 BeginDate/EndDate 值用于确定单位/成员在评估的月份/年份期间属于哪个子类别。

因此，结果集的简化形式如下所示：

Unit    New  Assumed        Existing    Organic     Total
----    ---  -------        --------    -------     -----
Abuelos $22  $44            $33         $11         $110
Gramps  $12  $23            $1          $34         $70
. . .

把这个问题用英语表达的话，就是这样的：

给定用户提供的月份和年份（例如“1”代表月份（一月），“2016”代表年份），找出每个单位该月内每个子类别的每月销售额有多少美元（其中BeginDate 小于或等于用户提供的月/年日期，并且 EndDate 大于或等于提供的月/年日期。

因此，我似乎需要从年/月参数创建一个日期，以便与 CustomerCategoryLog 表中的 BeginDate 和 EndDate 值进行比较（另一个选项是更改 CustomerCategoryLog 表，以便它具有 BeginDateMonth、BeginDateYear、EndDateMonth和 EndDateYear 整数；但我认为必须有一种简单的方法来根据提供的年/月参数创建日期）。

我的问题是如何在 TSQL 中实际构建它。我不是 SQLhead，我最好的（伪 SQL）尝试是：

DECLARE @Unit varchar(30);
DECLARE @Year Int;
DECLARE @Month Int;
. . .
DECLARE @PARAMDATE DATETIME = (Year + Month + 01).ToDateTime();

SELECT DISTINCT UNIT INTO #UNITS U FROM ReportingMonthlySales
WHILE NOT U.EOF DO

Unit = U.Unit

SELECT Unit, MonthlySales as 'NewSales' FROM (SELECT MonthlySales FROM ReportingMonthlySales RMS left join     
CustomerCategoryLog CCL on RMS.Unit = CCL.Unit WHERE RMS.Unit = Unit AND RMS.CYear = @Year and RMS.CMonth = @Month     
AND CCL.BeginDate >= PARAMDATE AND CCL.EndDate <= PARAMDATE AND CCL.Subcategory = 'New'),

MonthlySales as 'AssumedSales' FROM (SELECT MonthlySales FROM ReportingMonthlySales RMS left join     
CustomerCategoryLog CCL on RMS.Unit = CCL.Unit WHERE RMS.Unit = Unit AND  RMS.CYear = @Year and RMS.CMonth = @Month     
AND CCL.BeginDate >= PARAMDATE AND CCL.EndDate <= PARAMDATE AND CCL.Subcategory = 'Assumed'),

MonthlySales as 'ExistingSales' FROM (SELECT MonthlySales FROM ReportingMonthlySales RMS left join     
CustomerCategoryLog CCL on RMS.Unit = CCL.Unit WHERE RMS.Unit = Unit AND  RMS.CYear = @Year and RMS.CMonth = @Month     
AND CCL.BeginDate >= PARAMDATE AND CCL.EndDate <= PARAMDATE AND CCL.Subcategory = 'Existing'),

MonthlySales as 'OrganicSales' FROM (SELECT MonthlySales FROM ReportingMonthlySales RMS left join     
CustomerCategoryLog CCL on RMS.Unit = CCL.Unit WHERE RMS.Unit = Unit AND  RMS.CYear = @Year and RMS.CMonth = @Month     
AND CCL.BeginDate >= PARAMDATE AND CCL.EndDate <= PARAMDATE AND CCL.Subcategory = 'Organic')
FROM ReportingMonthlySales RMS2
ORDER BY RMS2.Unit

END WHILENOTEOF

我知道这不太正确，甚至可能根本不正确，但希望它对于 SQL 专家/初级人员来说足够清楚。读心术以了解我需要做什么/正在尝试做什么。

UPDATE

以下是查询的两个表中的一些示例数据：

客户类别日志表：

MemberNo = 007
Unit = AMC THEATERS
Subcategory = New
BeginDate = 1/1/2016
EndDate = 12/31/2016

MemberNo = 029
Unit = FOODBUY HMS
Subcategory = Existing
BeginDate = 1/1/2015
EndDate = 12/31/2015

报告每月销售表：

Unit = AMC THEATERS
MemberNo = 007
MonthlySales  = $988.82
CYear = 2016
Cmonth = 1

Unit = FOODBUY HMS
MemberNo = 029
MonthlySales  = $61,479.28
CYear = 2017
Cmonth = 3

这看起来像是一个漫长的转型之路。

像这样的事情怎么样？

declare @Unit varchar(30);
declare @Year int;
declare @Month int;
declare @paramdate datetime = datefromparts(@year, @month, 1);
/* --prior to sql server 2012
declare @paramdate datetime;
set @paramdate = convert(datetime,convert(char(4),@Year)
                +right('0'+convert(varchar(2),@month),2)
                +'01') 
*/

select distinct unit
into #Units
from ReportingMonthlySales;

select 
    u.Unit
  , New      = sum(case when ccl.Subcategory = 'New'      then rms.MonthlySales else 0 end)
  , Assumed  = sum(case when ccl.Subcategory = 'Assumed'  then rms.MonthlySales else 0 end)
  , Existing = sum(case when ccl.Subcategory = 'Existing' then rms.MonthlySales else 0 end)
  , Organic  = sum(case when ccl.Subcategory = 'Organic'  then rms.MonthlySales else 0 end)
from #Units u
  left join CustomerCategoryLog ccl 
    on u.Unit = ccl.Unit
   and @paramdate >= ccl.begindate
   and @paramdate <= ccl.enddate
  left join ReportingMonthlySales rms
    on u.Unit = rms.Unit
   and rms.cyear  = @year
   and rms.cmonth = @month
group by u.unit;