【发布时间】：2021-09-24 11:12:17
【问题描述】：
我在两个不同的数据库中工作。在创建报告（使用 TSQL）以在部门之间共享时，要求有一个字段来显示来自主数据库的信息（保存在学院数据库中的信息）也已输入到第二个数据库（特定部门使用用于与联邦计划的信息通信）。如果不使用 case 语句检查第二个数据库，则查询其余信息只需不到一秒的时间。使用 case 语句（在其中创建 CTE 以进行检查），它已经运行了 15 分钟，并且在我手动结束执行之前还没有完成。以下是代码（CASE 语句目前已注释掉）：
With POWERFAIDS_CHECK as
(
Select distinct NAME_MASTER.ID_NUM,
(CAST (NAME_MASTER.ID_NUM as VARCHAR) + CAST (EX_SCHOLARSHIP_RECIPIENTS.AID_ELEMENT as VARCHAR) ) as CHECK_ID
From NAME_MASTER
JOIN EX_SCHOLARSHIP_RECIPIENTS on NAME_MASTER.ID_NUM = EX_SCHOLARSHIP_RECIPIENTS.ID_NUM
JOIN SCHOLARSHIP on EX_SCHOLARSHIP_RECIPIENTS.AID_ELEMENT = SCHOLARSHIP.AID_ELEMENT
JOIN PF_FUND_CDE_MSTR on EX_SCHOLARSHIP_RECIPIENTS.AID_ELEMENT = PF_FUND_CDE_MSTR.RPT_CATEGORY
JOIN PowerFAIDS_Production.dbo.student on NAME_MASTER.ID_NUM = PowerFAIDS_Production.dbo.student.alternate_id
JOIN PowerFAIDS_Production.dbo.funds on PF_FUND_CDE_MSTR.FUND_CDE = PowerFAIDS_Production.dbo.funds.fund_ledger_number
JOIN PowerFAIDS_Production.dbo.stu_award_year on PowerFAIDS_Production.dbo.student.student_token = PowerFAIDS_Production.dbo.stu_award_year.student_token
JOIN PowerFAIDS_Production.dbo.stu_award on PowerFAIDS_Production.dbo.stu_award_year.stu_award_year_token = PowerFAIDS_Production.dbo.stu_award.stu_award_year_token
JOIN YEAR_TERM_TABLE on (YEAR_TERM_TABLE.YR_CDE = EX_SCHOLARSHIP_RECIPIENTS.YR_CDE) and (YEAR_TERM_TABLE.TRM_CDE = EX_SCHOLARSHIP_RECIPIENTS.TRM_CDE)
Where EX_SCHOLARSHIP_RECIPIENTS.YR_CDE = '2021'
and EX_SCHOLARSHIP_RECIPIENTS.TRM_CDE = 'FA'
and YEAR_TERM_TABLE.TRM_BEGIN_DTE = PowerFAIDS_Production.dbo.stu_award.award_period_begin_dt
and EX_SCHOLARSHIP_RECIPIENTS.AWARD_AMT = PowerFAIDS_Production.dbo.stu_award.actual_amt
and stu_award.status = 'A'
),
AWARDED_SCHOLARSHIPS as
(Select distinct NAME_MASTER.ID_NUM, (NAME_MASTER.FIRST_NAME + ' ' + NAME_MASTER.LAST_NAME) as STUDENT_NAME,
SCHOLARSHIP.DESCRIPTION,
Format (EX_SCHOLARSHIP_RECIPIENTS.AWARD_AMT, 'C','en-us') as AWARD_AMT,
EX_SCHOLARSHIP_RECIPIENTS.COMMENTS,
YR_DESC, TRM_DESC, EX_SCHOLARSHIP_RECIPIENTS.AID_ELEMENT,
(CAST (NAME_MASTER.ID_NUM as VARCHAR) + CAST (EX_SCHOLARSHIP_RECIPIENTS.AID_ELEMENT as VARCHAR) ) as CHECK_ID,
NAME_MASTER.LAST_NAME, NAME_MASTER.FIRST_NAME
From NAME_MASTER
JOIN EX_SCHOLARSHIP_RECIPIENTS on NAME_MASTER.ID_NUM = EX_SCHOLARSHIP_RECIPIENTS.ID_NUM
JOIN SCHOLARSHIP on EX_SCHOLARSHIP_RECIPIENTS.AID_ELEMENT = SCHOLARSHIP.AID_ELEMENT
JOIN YEAR_DEF on EX_SCHOLARSHIP_RECIPIENTS.YR_CDE = YEAR_DEF.YR_CDE
JOIN TERM_DEF on EX_SCHOLARSHIP_RECIPIENTS.TRM_CDE = TERM_DEF.TRM_CDE
Where EX_SCHOLARSHIP_RECIPIENTS.TRM_CDE = 'FA'
and EX_SCHOLARSHIP_RECIPIENTS.YR_CDE = '2021'
and EX_SCHOLARSHIP_RECIPIENTS.AID_ELEMENT not between '5000' and '5999'
)
Select distinct AWARDED_SCHOLARSHIPS.ID_NUM, STUDENT_NAME,
AWARDED_SCHOLARSHIPS.DESCRIPTION, AWARDED_SCHOLARSHIPS.AWARD_AMT,
--CASE
-- WHEN AWARDED_SCHOLARSHIPS.CHECK_ID not in (Select CHECK_ID from POWERFAIDS_CHECK)
-- THEN 'No'
-- ELSE 'Yes'
--END as Processed_FA_Award,
AWARDED_SCHOLARSHIPS.COMMENTS,
AWARDED_SCHOLARSHIPS.YR_DESC, AWARDED_SCHOLARSHIPS.TRM_DESC, AWARDED_SCHOLARSHIPS.LAST_NAME, AWARDED_SCHOLARSHIPS.FIRST_NAME
From AWARDED_SCHOLARSHIPS
LEFT OUTER JOIN POWERFAIDS_CHECK on AWARDED_SCHOLARSHIPS.ID_NUM = POWERFAIDS_CHECK.ID_NUM
Where AWARDED_SCHOLARSHIPS.ID_NUM in (Select ID_NUM from AWARDED_SCHOLARSHIPS)
Order by AWARDED_SCHOLARSHIPS.DESCRIPTION, LAST_NAME, FIRST_NAME
非常感谢任何见解，谢谢！
【问题讨论】：
-
Bad Habits to Kick : Declaring VARCHAR without (length)。还要养成给你的对象别名的习惯，它会让你的查询远更简洁，因此更易读。
-
您需要所有这些
DISTINCTs 吗？该运算符非常昂贵，通常如果您在上述查询中需要它，则表明您的JOINs 可能没有错。 -
当您离开连接到
POWERFAIDS_CHECK同时还在子查询中使用该表时，似乎有些错误。奇怪的是，您将不同的列用于看似相同的“连接”。架构问题通常会导致查询性能不佳。 -
如果您对 CHECK_ID 的计算涉及数字，您的代码可能会产生误导性信息。将元组 和 都转换为 '112'。
标签： sql-server tsql case common-table-expression