MySQL 约束未通过视图传递

Posted 2023-02-26

【中文标题】MySQL 约束未通过视图传递

【英文标题】：MySQL Restraint Not Being Passed Down Through Views

【发布时间】：2016-09-28 15:13:27

【问题描述】：

我正在使用一个具有多个相互链接的视图的系统。出于某种原因，有一个有问题的观点没有通过链条传递约束（尽管它们有一个共同的关键）。例如，这里是视觉解释语句。 Visual Explain of SQL View

如您所见，主视图基于另外两个视图（反过来，它们又基于另一组视图）。此示例中的问题视图是 ResourcePointsAndCategories（在右侧底部）。在此查询中，我通过基于名为 HostID 的列的 WHERE 子句来限制结果。 HostID 在我看来是支持的；但是，密钥没有被传递，因此，视图正在加载 23,000 行，而不是我想要的 3 行。

任何解释或更正此问题的帮助将不胜感激。谢谢！

编辑：对不起，应该从一开始就包含代码：

这里是主视图：

VIEW `test`.`resourcepointswithlookupsandcategorycountandportalpagescount` AS
SELECT 
    `resourcepointswithlookups`.`URL` AS `URL`,
    `resourcepointswithlookups`.`Format` AS `Format`,
    `resourcepointswithlookups`.`Host` AS `Host`,
    `resourcepointswithlookups`.`ResourceID` AS `ResourceID`,
    `resourcepointswithlookups`.`HostID` AS `HostID`,
    `resourcepointswithlookups`.`PermitID` AS `PermitID`,
    `resourcepointswithlookups`.`ResourceTitle` AS `ResourceTitle`,
    `resourcepointswithlookups`.`FormatID` AS `FormatID`,
    `resourcepointswithlookups`.`TypeID` AS `TypeID`,
    `resourcepointswithlookups`.`Notes` AS `Notes`,
    `resourcepointswithlookups`.`Description` AS `Description`,
    `resourcepointswithlookups`.`ReferenceFirstName` AS `ReferenceFirstName`,
    `resourcepointswithlookups`.`ReferenceLastName` AS `ReferenceLastName`,
    `resourcepointswithlookups`.`ReferenceEmail` AS `ReferenceEmail`,
    `resourcepointswithlookups`.`ReferencePermission` AS `ReferencePermission`,
    `resourcepointswithlookups`.`ReferenceComment` AS `ReferenceComment`,
    `resourcepointswithlookups`.`CreateDate` AS `CreateDate`,
    `resourcepointswithlookups`.`CreateBy` AS `CreateBy`,
    `resourcepointswithlookups`.`LastEditDate` AS `LastEditDate`,
    `resourcepointswithlookups`.`LastEditBy` AS `LastEditBy`,
    `resourcepointswithlookups`.`LastReview` AS `LastReview`,
    `resourcepointswithlookups`.`LastReviewBy` AS `LastReviewBy`,
    `resourcepointswithlookups`.`Type` AS `Type`,
    `resourcepointswithlookups`.`LibraryURL` AS `LibraryURL`,
    `resourcepointswithlookups`.`TypeCollection` AS `TypeCollection`,
    `resourcepointsandcategoriescount`.`CategoryCount` AS `CategoryCount`,
    `portalpagecountwithresourcepointsandportaltitle`.`PortalPageCount` AS `PortalPageCount`,
    `resourcepointswithlookups`.`NormFileStatus` AS `NormFileStatus`,
    `resourcepointswithlookups`.`NormFileStatusDate` AS `NormFileStatusDate`,
    `resourcepointswithlookups`.`FileSystemStatus` AS `FileSystemStatus`,
    `resourcepointswithlookups`.`FileSystemStatusDate` AS `FileSystemStatusDate`,
    `resourcepointswithlookups`.`LanguageName` AS `LanguageName`,
    `resourcepointswithlookups`.`LanguageCode` AS `LanguageCode`
FROM
    ((`test`.`resourcepointswithlookups`
    LEFT JOIN `test`.`portalpagecountwithresourcepointsandportaltitle` ON ((`resourcepointswithlookups`.`ResourceID` = `portalpagecountwithresourcepointsandportaltitle`.`ResourcePointID`)))
    LEFT JOIN `test`.`resourcepointsandcategoriescount` ON ((`resourcepointswithlookups`.`ResourceID` = `resourcepointsandcategoriescount`.`ResourceID`)))

这是问题视图的代码：

VIEW `test`.`resourcepointsandcategoriescount` AS
SELECT 
    `resourcepointsandcategories`.`ResourceID` AS `ResourceID`,
    `resourcepointsandcategories`.`HostID` AS `HostID`,
    COUNT(`resourcepointsandcategories`.`CategoryID`) AS `CategoryCount`
FROM
    `test`.`resourcepointsandcategories`
GROUP BY `resourcepointsandcategories`.`ResourceID`

最终，问题视图所基于的视图（运行良好）：

VIEW `test`.`resourcepointsandcategories` AS
SELECT 
    `test`.`resourcepoints`.`ResourceID` AS `ResourceID`,
    `test`.`resourcepoints`.`HostID` AS `HostID`,
    `test`.`lkupegcategories`.`Category` AS `Category`,
    `test`.`resourcepointcategories`.`CategoryID` AS `CategoryID`
FROM
    ((`test`.`resourcepointcategories`
    JOIN `test`.`resourcepoints` ON ((`test`.`resourcepointcategories`.`ResourceID` = `test`.`resourcepoints`.`ResourceID`)))
    LEFT JOIN `test`.`lkupegcategories` ON ((`test`.`lkupegcategories`.`eGCategoryID` = `test`.`resourcepointcategories`.`CategoryID`)))

我正在调用的查询是：

 SELECT * FROM test.resourcepointswithlookupsandcategorycountandportalpagescount WHERE HostID = 4532;

【问题讨论】：

请向我们展示您的一些代码，以便我们提供适当的帮助

添加代码！谢谢！

请提供EXPLAIN SELECT ...

【参考方案1】：

如果我正确阅读了您的观点，您将过滤HostID = 4532 上的第一个（大）视图，而不是过滤其他两个视图。

也许ON 子句需要包含AND res....HostID = res...HostID。