SQL

Question

我正在写一份很长的报告，它运行时没有错误，但即使我使用 'select distinct' 它仍然为我尝试报告的每个唯一值显示 11 行。

我需要为每个不同的事件仅显示 1 行的唯一值是案例编号，或 'cases.casenum'。
我已经包含了输出的屏幕截图，它非常清楚地说明了我要做什么......这是代码：

SELECT distinct
(
SELECT count(distinct cases.casenum)
FROM (cases INNER JOIN user_case_data ON cases.casenum=user_case_data.casenum)
WHERE (user_case_data.discharged_date &gt;= '##START##'
AND user_case_data.discharged_date &lt;= '##END##')
)
AS "Total Lost Files", cases.casenum AS "Case Number", user_case_data.discharged_date AS "Discharged Date",

(case when case_notes.topic like 'LOS Case Status Update' THEN case_notes.note_date else null end)
AS "Gendoc #31 Mailed",

(case when case_checklist.code='101' then case_checklist.due_date else null end)
AS "Advised Attorney",

(case when case_notes.topic like 'LOS Updated Lein Ltr' THEN case_notes.note_date else null end)
AS "Sent Updated Lien Ltr",

(case when case_checklist.code='109' then case_checklist.due_date else null end)
AS "Time Allocation Completed",

(case when case_checklist.code='110' then case_checklist.due_date else null end)
AS "Attorney Signed Affidavit",

(case when case_checklist.code='111' then case_checklist.due_date else null end)
AS "Lien Letters Sent",

(case when case_checklist.code='112' then case_checklist.due_date else null end)
AS "Sent Lien to Counsel",

(case when case_checklist.code='113' then case_checklist.due_date else null end)
AS "Received Costs and Transferred"

FROM (cases LEFT JOIN case_checklist ON cases.casenum=case_checklist.case_id
LEFT JOIN user_case_data ON case_checklist.case_id=user_case_data.casenum
LEFT JOIN case_notes ON user_case_data.casenum=case_notes.case_num)
WHERE (user_case_data.discharged_date &gt;= '##START##'
AND user_case_data.discharged_date &lt;= '##END##')
ORDER BY user_case_data.discharged_date ASC;

附加信息：
- 每个案号只有一个出院日期。所以对于每一行，应该只有 1 个病例编号和 1 个出院日期。
- case_notes 和 case_checklist 表中的每个案例编号可能存在许多记录，但是我只是想提取 1 个单个注释的日期（在案例语句中指定主题），并且1 个清单项目（在案例陈述中再次指定）
- 第一列并不是真正必要的，我没有理由要计算每行的案例总数......我只是想在输出中的某个地方进行总计数，但不知道我还能怎么做.

Answer 1

正如 JustinStolle 所建议的那样，他对聚合函数和 GROUP BY 的建议是正确的：

SELECT 
(
SELECT count(distinct cases.casenum)
FROM (cases INNER JOIN user_case_data ON cases.casenum=user_case_data.casenum)
WHERE (user_case_data.discharged_date &gt;= '##START##'
AND user_case_data.discharged_date &lt;= '##END##')
)
AS "Total Lost Files", cases.casenum AS "Case Number", user_case_data.discharged_date AS "Discharged Date",

MAX(case when case_notes.topic like 'LOS Case Status Update' THEN case_notes.note_date else null end)
AS GENDOC_31_Mailed,

MAX(case when case_checklist.code='101' then case_checklist.due_date else null end)
AS ADVISED_ATTORNEY,

MAX(case when case_notes.topic like 'LOS Updated Lein Ltr' THEN case_notes.note_date else null end)
AS "Sent Updated Lien Ltr",

MAX(case when case_checklist.code='109' then case_checklist.due_date else null end)
AS "Time Allocation Completed",

MAX(case when case_checklist.code='110' then case_checklist.due_date else null end)
AS "Attorney Signed Affidavit",

MAX(case when case_checklist.code='111' then case_checklist.due_date else null end)
AS "Lien Letters Sent",

MAX(case when case_checklist.code='112' then case_checklist.due_date else null end)
AS "Sent Lien to Counsel",

MAX(case when case_checklist.code='113' then case_checklist.due_date else null end)
AS "Received Costs and Transferred"

FROM cases 
LEFT JOIN case_checklist ON cases.casenum = case_checklist.case_id
LEFT JOIN user_case_data ON case_checklist.case_id=user_case_data.casenum
LEFT JOIN case_notes ON user_case_data.casenum=case_notes.case_num AND case_notes.topic LIKE 'LOS Case Status Update'
WHERE (user_case_data.discharged_date &gt;= '##START##'
AND user_case_data.discharged_date &lt;= '##END##')
GROUP BY cases.casenum, user_case_data.discharged_date
ORDER BY user_case_data.discharged_date ASC;

SQL - 如何使用 GROUP BY 为每个不同的值 select 1 行

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