根据入参查询table

Question

我有一个我正在尝试编写的查询的输入参数。基本上，if mostRecentSnapshot == true 然后我只想 select 过程中的最新记录运行（基本上 where max(creationDate)）和 if mostRecentSnapshot == false 然后 select creationDate 和其他列正常。

对我来说，在 from 子句中执行此 if 语句是有意义的，但我认为这是不可能的。通常我会使用 CTE，但 MySQL.

中不存在这些

实现此目标的最佳方法是什么？

大概是这样的：

SELECT
CASE mostRecentSnapshot WHEN FALSE THEN 
(
processauditheader.creationDate as processCreationDate,
processauditheader.processName,
processauditheader.processType,
processauditheader.processHost,
processauditheader.processDatabase,
processauditheader.tableAudited,
processauditheader.processInvokedByName,
processauditheader.processInvokedByType,
processauditheader.processInvokedByDatabase,
processauditheader.processIntervalValue,
processauditheader.processIntervalField,
processauditheader.auditScenarios,
processaudititerationdetail.creationDate as iterationDate,
processaudititerationdetail.connectionId,
processaudititerationdetail.processDate,
processaudititerationdetail.tableRowCount,
processaudititerationdetail.tableRowCountLastDay,
processaudititerationdetail.previousProcessAuditIterationDetailID,
processauditmetricdetail.creationDate,
processauditmetricdetail.processAuditIterationDetailID,
processauditmetricdetail.auditMetric,
processauditmetricdetail.auditTotal,
processauditmetricdetail.auditExample
)
WHEN TRUE THEN 
(
((SELECT MAX(processaudititerationdetail.creationDate) as maxSnapshot,
processaudititerationdetail.id
from reporting_audit.processaudititerationdetail
group by processaudititerationdetail.creationDate) mostRecent

JOIN reporting_audit.processaudititerationdetail ON mostRecent.id = processaudititerationdetail.id)
)
END

FROM reporting_audit.processauditheader

JOIN processaudititerationdetail ON processaudititerationdetail.processAuditHeaderID = processauditheader.id
LEFT JOIN processauditmetricdetail ON processauditmetricdetail.processAuditIterationDetailID = processaudititerationdetail.id

Answer 1

一个查询只能return一组固定的列。也许以下内容可以满足您的需求：

select paid.*
from reporting_audit.processaudititerationdetail paid
where (not v_mostRecentSnapshot) or
      paid.creation_date = (select max(paid2.creationDate from reporting_audit.processaudititerationdetail paid2);

它将 select 来自 table 的所有记录或仅包含最近 creationDate.

的记录

根据入参查询table

Query table based on input parameter

mysql

conditional