MySQL 查询（子查询 + 组合函数 + JOIN 操作）花费的时间太长 运行
MySQL Query (Sub Queries + Composed Functions + JOIN operations) takes too long to run
如何使用由函数组成的子查询和函数中的连接查询修改以下查询。我想在多次依赖主 tables 和两个主要连接（风险、用户）的主查询中附加额外的值。
创建 MCVRE（最小完整可验证可重现示例）被证明是有点挑战，因为发送到 SQL 的请求 Fiddle 有太多行（太多文本字符）删除几乎所有行后在主要的两个 tables（用户、风险）上，我得到了一个 运行ning 查询。
Fiddle (http://www.sqlfiddle.com/#!9/1d52a0/17) 创建函数和插入数据命令减少了我本地 PC 上实际示例中的行数，因为 [=51] 的请求负载超过了 8000 个字符数=]Fiddle明白了。
实际table有大约100行风险，20行左右用户，需要大约3秒到运行
我可以做些什么来加速查询，通过在 table 中保存所需的函数结果，或者通过修改、索引插入、将连接移动到外部主查询，甚至使用存储过程，或重写查询结构，以将执行时间减少到可能一半或不太乐观。 SQL fiddle 没有获取所有需要的行，所以我粘贴了一个非常有限的子集，即使是 SQLFiddle 查询（参见下面的总 select 查询）也没有 运行，由于堆栈溢出（双关语部分意图）。
http://www.sqlfiddle.com/#!9/1d52a0/17
在 fiddle 上执行 运行 的基本查询（参见 fiddle）
select * from users;
select * from risks;
select * from riskevents;
select * from riskmatrixthresholds;
select * from risklevels;
#显着减少了结果集，但由于 sql fiddle 上的堆栈溢出问题，查询仍然没有 运行 - 请参阅 fiddle 结果（在最底部fiddle 查询输出)
SELECT r.RiskID,
r.CreatorID,
r.OwnerID,
r.ApproverID,
r.RiskTitle,
r.RiskStatement,
r.ClosureCriteria,
r.RiskState,
r.Context AS 'Context',
GetRiskUserLastOrFirstName(GetRiskUserID('Creator', r.RiskID,0),r.RiskID, 'Last','') AS 'creator.lastname',
GetRiskUserLastOrFirstName(GetRiskUserID('Creator', r.RiskID,0),r.RiskID, 'First','') AS 'creator.firstname',
GetRiskUserLastOrFirstName(GetRiskUserID('Owner', r.RiskID,0),r.RiskID, 'Last','') AS 'owner.lastname',
GetRiskUserLastOrFirstName(GetRiskUserID('Owner', r.RiskID,0),r.RiskID, 'First','') AS 'owner.firstname',
GetRiskUserLastOrFirstName(GetRiskUserID('Approver',r.RiskID,0),r.RiskID, 'Last','') AS 'approver.lastname',
GetRiskUserLastOrFirstName(GetRiskUserID('Approver',r.RiskID,0),r.RiskID, 'First','') AS 'approver.firstname',
r.Likelihood AS 'OriginalLikelihood',
r.Technical AS 'OriginalTechnical',
r.Schedule AS 'OriginalSchedule',
r.Cost AS 'OriginalCost',
GREATEST(r.Technical, r.Schedule, r.Cost) AS 'OriginalConsequence',
RiskValue(r.Likelihood, GREATEST(r.Technical, r.Schedule, r.Cost),0) AS 'OriginalValue',
RiskLevel(RiskValue(r.Likelihood, GREATEST(r.Technical, r.Schedule, r.Cost),0),'') AS 'OriginalLevel',
LatestEventDate(r.RiskID, r.AssessmentDate,'') AS 'LatestEventDate',
r.AssessmentDate AS 'AssessmentDate',
(SELECT CurrentLikelihood(r.RiskID,0)) AS 'CurrentLikelihood',
(SELECT CurrentConsequence(r.RiskID,0)) AS 'CurrentConsequence',
(SELECT CurrentRiskValue(r.RiskID,0)) AS 'CurrentValue',
(SELECT RiskLevel(CurrentRiskValue(r.RiskID,0),'')) AS 'CurrentLevel'
FROM risks r;
创建函数脚本
CREATE TABLE `riskevents` (
`ID` int NOT NULL AUTO_INCREMENT,
`EventID` int ,
`RiskID` int ,
`EventTitle` text,
`EventStatus` varchar(10) ,
`EventOwnerID` int ,
`ActualDate` date ,
`ScheduleDate` date ,
`BaselineDate` date ,
`ActualLikelihood` int ,
`ActualTechnical` int ,
`ActualSchedule` int ,
`ActualCost` int ,
`ScheduledLikelihood` int ,
`ScheduledTechnical` int ,
`ScheduledSchedule` int ,
`ScheduledCost` int ,
`BaselineLikelihood` int ,
`BaselineTechnical` int ,
`BaselineSchedule` int ,
`BaselineCost` int ,
PRIMARY KEY (`ID`)
)
CREATE TABLE `risklevels` (
`ID` int NOT NULL AUTO_INCREMENT,
`RiskLevelID` int ,
`RiskMaximum` float ,
`RiskHigh` float ,
`RiskMedium` float ,
`RiskMinimum` float ,
PRIMARY KEY (`ID`)
)
CREATE TABLE `riskmatrixthresholds` (
`ID` int NOT NULL AUTO_INCREMENT,
`CellID` int ,
`Likelihood` int ,
`Consequence` int ,
`Level` decimal(2,2) ,
PRIMARY KEY (`ID`)
)
CREATE TABLE `risks` (
`ID` int NOT NULL AUTO_INCREMENT,
`RiskState` varchar(10) ,
`RiskID` int ,
`RiskTitle` text CHARACTER SET latin1,
`RiskStatement` text CHARACTER SET latin1,
`ApproverID` int ,
`OwnerID` int ,
`CreatorID` int ,
`Likelihood` int ,
`Technical` int ,
`Schedule` int ,
`Cost` int ,
`ClosureCriteria` text CHARACTER SET latin1,
`CategoryID` int ,
`AssessmentDate` date ,
`CompletionDate` date ,
`ClosureDate` date ,
`Context` text,
PRIMARY KEY (`ID`),
UNIQUE KEY `risk_index` (`RiskID`)
)
CREATE TABLE `users` (
`ID` int NOT NULL AUTO_INCREMENT,
`UserID` int NOT NULL,
`LastName` char(25) ,
`FirstName` char(15) ,
`Title` char(20) ,
`Email` varchar(30) ,
`Phone` char(12) ,
`Extension` char(4) ,
`Department` char(25) ,
PRIMARY KEY (`ID`),
UNIQUE KEY `user_index` (`UserID`),
KEY `SURROGATE` (`UserID`)
)
insert into `riskevents`(`ID`,`EventID`,`RiskID`,`EventTitle`,`EventStatus`,`EventOwnerID`,`ActualDate`,`ScheduleDate`,`BaselineDate`,`ActualLikelihood`,`ActualTechnical`,`ActualSchedule`,`ActualCost`,`ScheduledLikelihood`,`ScheduledTechnical`,`ScheduledSchedule`,`ScheduledCost`,`BaselineLikelihood`,`BaselineTechnical`,`BaselineSchedule`,`BaselineCost`) values
(171,0,1,'Risk','Complete',5,'2019-06-14',NULL,'2019-06-14',5,2,2,5,NULL,NULL,NULL,NULL,5,2,2,5),
(184,0,10,'Risk','Complete',21,'2019-10-07',NULL,'2019-10-07',5,4,5,4,NULL,NULL,NULL,NULL,5,4,5,4));
insert into `risklevels`(`ID`,`RiskLevelID`,`RiskMaximum`,`RiskHigh`,`RiskMedium`,`RiskMinimum`) values
(1,1,1,0.55,0.3,0);
insert into `riskmatrixthresholds`(`ID`,`CellID`,`Likelihood`,`Consequence`,`Level`) values
(1,1,1,1,0.09),
(2,2,1,2,0.12),
(3,3,1,3,0.16),
(4,4,1,4,0.19),
(5,5,1,5,0.23),
(6,6,2,1,0.12),
(7,7,2,2,0.19),
(8,8,2,3,0.27),
(9,9,2,4,0.34),
(10,10,2,5,0.41),
(11,11,3,1,0.16),
(12,12,3,2,0.27),
(13,13,3,3,0.37),
(14,14,3,4,0.48),
(15,15,3,5,0.59),
(16,16,4,1,0.19),
(17,17,4,2,0.34),
(18,18,4,3,0.48),
(19,19,4,4,0.63),
(20,20,4,5,0.77),
(21,21,5,1,0.23),
(22,22,5,2,0.41),
(23,23,5,3,0.59),
(24,24,5,4,0.77),
(25,25,5,5,0.95);
insert into `risks`(`ID`,`RiskState`,`RiskID`,`RiskTitle`,`RiskStatement`,`ApproverID`,`OwnerID`,`CreatorID`,`Likelihood`,`Technical`,`Schedule`,`Cost`,`ClosureCriteria`,`CategoryID`,`AssessmentDate`,`CompletionDate`,`ClosureDate`,`Context`) values
(1,'Completed',1,'t','t',1,5,1,5,2,2,5,'t',NULL,'2019-06-14','2020-09-26',NULL,'t'),
(2,'Completed',2,'t','t',2,1,1,5,3,4,2,'test',NULL,'2019-05-14',NULL,NULL,'t'),
insert into `users`(`ID`,`UserID`,`LastName`,`FirstName`,`Title`,`Email`,`Phone`,`Extension`,`Department`) values
(1,1,'Admin','','Admin','a@yz.com','17890','1234',''),
(2,2,'Last','First','Engineer','a@yz.com','123890','1234','Supplier');
CREATE FUNCTION Consequence(technical int, sched int, cost int, consequence int) RETURNS int
BEGIN
select GREATEST(technical, sched, cost) into consequence;
return consequence;
END;
CREATE FUNCTION CurrentRiskEventID(riskidentifier int, eid int) RETURNS int
BEGIN
select MAX(e.EventID) into eid
FROM riskevents e
WHERE e.eventstatus not in('Open')
AND e.riskid = riskidentifier;
return riskeventid;
END;
CREATE FUNCTION CurrentConsequence(riskidentifier int, currentconsequence int) RETURNS int
BEGIN
SELECT coalesce(
(SELECT GREATEST(actualtechnical, actualschedule, actualcost)
FROM riskevents
WHERE id = CurrentRiskEventID(riskidentifier, 0)
and actualtechnical is not null
ANDactualschedule is not null
andactualschedule is not null),
(SELECT greatest(technical, schedule, cost)
from risks
Where riskid = riskidentifier)
) into currentconsequence;
return currentconsequence;
END;
CREATE FUNCTION CurrentLikelihood(riskidentifier int, currentlikelihood int) RETURNS int
BEGIN
SELECT coalesce(
(SELECT actuallikelihood
FROM riskevents
WHERE id = CurrentRiskEventID(riskidentifier, 0)),
(SELECT r.likelihood
FROM risks r
WHERE r.riskid = riskidentifier)) into currentlikelihood;
return currentlikelihood;
END;
CREATE FUNCTION CurrentRiskLevel(riskidentifier int, currentrisklevel int) RETURNS int
BEGIN
select RiskLevel(CurrentRiskValue(riskidentifier, 0), '') into currentrisklevel;
return currentrisklevel;
END;
CREATE FUNCTION CurrentRiskValue(riskidentifier int, currentriskvalue int) RETURNS int
BEGIN
SELECT RiskValue(CurrentLikelihood(riskidentifier, 0), CurrentConsequence(riskidentifier, 0), 0) into currentriskvalue;
return currentriskvalue;
END;
CREATE FUNCTION GetRiskUserID(riskusertype VARCHAR(25), riskidentifier int, riskuserid int) RETURNS int
BEGIN
SELECT COALESCE(userres.userid, 0) into riskuserid FROM
(
SELECT r.creatorid, r.ownerid, r.approverid, u.userid
FROM risks r, users u
WHERE r.riskid = (select riskidentifier) and
(
((select riskusertype) = 'Creator' AND u.userid = r.creatorid) OR
((select riskusertype) = 'Approver' AND u.userid = r.approverid) OR
((select riskusertype) = 'Owner' AND u.userid = r.ownerid)
)
) userres;
RETURN riskuserid;
END;
CREATE FUNCTION GetRiskUserLastOrFirstName(riskuserid int, riskid int, whichname char(25), firstorlastname char(25)) RETURNS char(25) CHARSET utf8 COLLATE utf8_unicode_ci
BEGIN
SELECT (case
when whichname = 'Last' then u.LastName
WHEN whichname = 'First' THEN u.FirstName
end)
into firstorlastname
FROM users u,risks r
WHERE u.UserID = riskuserid
AND r.RiskID = riskid;
return firstorlastname;
END;
CREATE FUNCTION LatestEventDate(riskidentifier int, riskassessmentdate date, latestdate date) RETURNS date
BEGIN
SELECT COALESCE(
(SELECT ActualDate FROM riskevents evt WHERE evt.eventid = CurrentRiskEventID(riskidentifier, 0) and evt.riskid = riskidentifier),
(SELECT riskassessmentdate)) into latestdate;
return latestdate;
END;
CREATE FUNCTION RiskLevel(riskvalue int, risklevel varchar(4)) RETURNS varchar(4)
begin
SELECT
CASE
WHEN riskvalue >= levels.riskhigh*100 THEN 'High'
WHEN riskvalue >= levels.riskmedium*100 THEN 'Med'
ELSE 'Low'
ENd as cat into risklevel
FROM risklevels levels;
return risklevel;
END;
CREATE FUNCTION RiskValue(likelihood int, consequence int, riskvalue int) RETURNS int
BEGIN
SELECT m.level*100 INTO riskvalue FROM riskmatrixthresholds m WHERE m.likelihood = likelihood AND m.consequence = consequence;
RETURN riskvalue;
END;
注意：SQL 是一种 声明式 语言，而不是 过程式 语言。你告诉它你想要什么，而不是如何得到它。您对函数等的使用是过程性的。
如何让这个应用程序更快？
首先，使用最新版本的MySQL（8+，或MariaDB 10.4+）。更高版本变得更快。
其次，您提出了使用“由函数组成的子查询”的要求。这意味着您可能对性能无能为力。
为什么不呢？隐藏在函数中的子查询是所谓的依赖子查询。那些表现不佳。而且因为它们被埋没了 MySQL 的查询规划器无法做任何有用的事情来优化它们。
重构您的查询以避免使用具有 SELECT 操作的函数将使查询规划器能够了解您的整体查询。这将使它有机会优化事物。您可以将它们替换为视图。
并且不要使用 SELECT tablea, tableb 语法。自 1992 年以来就已经过时了。使用
SELECT tablea JOIN tableb ON tablea.joincolumn = tableb.joincolumn.
我会为您提供更多建议，但我无法弄清楚您的意图。
在 CurrentLikelihood() 和 CurrentConsequence() 中应用以下更改将总查询执行时间减少到 exec 0.070 秒，总计 0.082 秒。
旧的当前可能性查询（产生缓慢且不正确的输出）
SELECT coalesce(
(SELECT actuallikelihood
FROM riskevents
WHERE id = CurrentRiskEventID(riskidentifier, 0)),
(SELECT r.likelihood
FROM risks r
WHERE r.riskid = riskidentifier)) into currentlikelihood;
return currentlikelihood;
工作电流可能性查询
SELECT actuallikelihood INTO currentlikelihood
FROM riskevents
WHERE eventid = CurrentRiskEventID(riskidentifier)
AND riskid = riskidentifier;
旧的 CurrentConsequence 查询（生成缓慢且不正确的输出）
SELECT coalesce(
(SELECT GREATEST(actualtechnical, actualschedule, actualcost)
FROM riskevents
WHERE id = CurrentRiskEventID(riskidentifier, 0)
and actualtechnical is not null
and actualschedule is not null),
(SELECT greatest(technical, schedule, cost)
from risks
Where riskid = riskidentifier)
) into currentconsequence;
工作电流结果查询
SELECT GREATEST(actualtechnical, actualschedule, actualcost) INTO currentconsequence
FROM riskevents
WHERE eventid = CurrentRiskEventID(riskidentifier)
AND riskid = riskidentifier;
旧 CurrentRiskEventID() 查询
select MAX(e.EventID) into currentriskeventid
FROM riskevents e
WHERE e.eventstatus not in('Open')
AND e.riskid = riskidentifier;
修改后的 GetRiskEventID() 函数
SELECT MAX(e.EventID) INTO currentriskeventid
FROM riskevents e
WHERE e.riskid = riskidentifier AND
(e.eventstatus != 'Open'
OR
(e.EventID = 0 AND e.eventstatus = 'Open'));
如何使用由函数组成的子查询和函数中的连接查询修改以下查询。我想在多次依赖主 tables 和两个主要连接（风险、用户）的主查询中附加额外的值。
创建 MCVRE（最小完整可验证可重现示例）被证明是有点挑战，因为发送到 SQL 的请求 Fiddle 有太多行（太多文本字符）删除几乎所有行后在主要的两个 tables（用户、风险）上，我得到了一个 运行ning 查询。
Fiddle (http://www.sqlfiddle.com/#!9/1d52a0/17) 创建函数和插入数据命令减少了我本地 PC 上实际示例中的行数，因为 [=51] 的请求负载超过了 8000 个字符数=]Fiddle明白了。
实际table有大约100行风险，20行左右用户，需要大约3秒到运行
我可以做些什么来加速查询，通过在 table 中保存所需的函数结果，或者通过修改、索引插入、将连接移动到外部主查询，甚至使用存储过程，或重写查询结构，以将执行时间减少到可能一半或不太乐观。 SQL fiddle 没有获取所有需要的行，所以我粘贴了一个非常有限的子集，即使是 SQLFiddle 查询（参见下面的总 select 查询）也没有 运行，由于堆栈溢出（双关语部分意图）。
http://www.sqlfiddle.com/#!9/1d52a0/17
在 fiddle 上执行 运行 的基本查询（参见 fiddle）
select * from users;
select * from risks;
select * from riskevents;
select * from riskmatrixthresholds;
select * from risklevels;
#显着减少了结果集，但由于 sql fiddle 上的堆栈溢出问题，查询仍然没有 运行 - 请参阅 fiddle 结果（在最底部fiddle 查询输出)
SELECT r.RiskID,
r.CreatorID,
r.OwnerID,
r.ApproverID,
r.RiskTitle,
r.RiskStatement,
r.ClosureCriteria,
r.RiskState,
r.Context AS 'Context',
GetRiskUserLastOrFirstName(GetRiskUserID('Creator', r.RiskID,0),r.RiskID, 'Last','') AS 'creator.lastname',
GetRiskUserLastOrFirstName(GetRiskUserID('Creator', r.RiskID,0),r.RiskID, 'First','') AS 'creator.firstname',
GetRiskUserLastOrFirstName(GetRiskUserID('Owner', r.RiskID,0),r.RiskID, 'Last','') AS 'owner.lastname',
GetRiskUserLastOrFirstName(GetRiskUserID('Owner', r.RiskID,0),r.RiskID, 'First','') AS 'owner.firstname',
GetRiskUserLastOrFirstName(GetRiskUserID('Approver',r.RiskID,0),r.RiskID, 'Last','') AS 'approver.lastname',
GetRiskUserLastOrFirstName(GetRiskUserID('Approver',r.RiskID,0),r.RiskID, 'First','') AS 'approver.firstname',
r.Likelihood AS 'OriginalLikelihood',
r.Technical AS 'OriginalTechnical',
r.Schedule AS 'OriginalSchedule',
r.Cost AS 'OriginalCost',
GREATEST(r.Technical, r.Schedule, r.Cost) AS 'OriginalConsequence',
RiskValue(r.Likelihood, GREATEST(r.Technical, r.Schedule, r.Cost),0) AS 'OriginalValue',
RiskLevel(RiskValue(r.Likelihood, GREATEST(r.Technical, r.Schedule, r.Cost),0),'') AS 'OriginalLevel',
LatestEventDate(r.RiskID, r.AssessmentDate,'') AS 'LatestEventDate',
r.AssessmentDate AS 'AssessmentDate',
(SELECT CurrentLikelihood(r.RiskID,0)) AS 'CurrentLikelihood',
(SELECT CurrentConsequence(r.RiskID,0)) AS 'CurrentConsequence',
(SELECT CurrentRiskValue(r.RiskID,0)) AS 'CurrentValue',
(SELECT RiskLevel(CurrentRiskValue(r.RiskID,0),'')) AS 'CurrentLevel'
FROM risks r;
创建函数脚本
CREATE TABLE `riskevents` (
`ID` int NOT NULL AUTO_INCREMENT,
`EventID` int ,
`RiskID` int ,
`EventTitle` text,
`EventStatus` varchar(10) ,
`EventOwnerID` int ,
`ActualDate` date ,
`ScheduleDate` date ,
`BaselineDate` date ,
`ActualLikelihood` int ,
`ActualTechnical` int ,
`ActualSchedule` int ,
`ActualCost` int ,
`ScheduledLikelihood` int ,
`ScheduledTechnical` int ,
`ScheduledSchedule` int ,
`ScheduledCost` int ,
`BaselineLikelihood` int ,
`BaselineTechnical` int ,
`BaselineSchedule` int ,
`BaselineCost` int ,
PRIMARY KEY (`ID`)
)
CREATE TABLE `risklevels` (
`ID` int NOT NULL AUTO_INCREMENT,
`RiskLevelID` int ,
`RiskMaximum` float ,
`RiskHigh` float ,
`RiskMedium` float ,
`RiskMinimum` float ,
PRIMARY KEY (`ID`)
)
CREATE TABLE `riskmatrixthresholds` (
`ID` int NOT NULL AUTO_INCREMENT,
`CellID` int ,
`Likelihood` int ,
`Consequence` int ,
`Level` decimal(2,2) ,
PRIMARY KEY (`ID`)
)
CREATE TABLE `risks` (
`ID` int NOT NULL AUTO_INCREMENT,
`RiskState` varchar(10) ,
`RiskID` int ,
`RiskTitle` text CHARACTER SET latin1,
`RiskStatement` text CHARACTER SET latin1,
`ApproverID` int ,
`OwnerID` int ,
`CreatorID` int ,
`Likelihood` int ,
`Technical` int ,
`Schedule` int ,
`Cost` int ,
`ClosureCriteria` text CHARACTER SET latin1,
`CategoryID` int ,
`AssessmentDate` date ,
`CompletionDate` date ,
`ClosureDate` date ,
`Context` text,
PRIMARY KEY (`ID`),
UNIQUE KEY `risk_index` (`RiskID`)
)
CREATE TABLE `users` (
`ID` int NOT NULL AUTO_INCREMENT,
`UserID` int NOT NULL,
`LastName` char(25) ,
`FirstName` char(15) ,
`Title` char(20) ,
`Email` varchar(30) ,
`Phone` char(12) ,
`Extension` char(4) ,
`Department` char(25) ,
PRIMARY KEY (`ID`),
UNIQUE KEY `user_index` (`UserID`),
KEY `SURROGATE` (`UserID`)
)
insert into `riskevents`(`ID`,`EventID`,`RiskID`,`EventTitle`,`EventStatus`,`EventOwnerID`,`ActualDate`,`ScheduleDate`,`BaselineDate`,`ActualLikelihood`,`ActualTechnical`,`ActualSchedule`,`ActualCost`,`ScheduledLikelihood`,`ScheduledTechnical`,`ScheduledSchedule`,`ScheduledCost`,`BaselineLikelihood`,`BaselineTechnical`,`BaselineSchedule`,`BaselineCost`) values
(171,0,1,'Risk','Complete',5,'2019-06-14',NULL,'2019-06-14',5,2,2,5,NULL,NULL,NULL,NULL,5,2,2,5),
(184,0,10,'Risk','Complete',21,'2019-10-07',NULL,'2019-10-07',5,4,5,4,NULL,NULL,NULL,NULL,5,4,5,4));
insert into `risklevels`(`ID`,`RiskLevelID`,`RiskMaximum`,`RiskHigh`,`RiskMedium`,`RiskMinimum`) values
(1,1,1,0.55,0.3,0);
insert into `riskmatrixthresholds`(`ID`,`CellID`,`Likelihood`,`Consequence`,`Level`) values
(1,1,1,1,0.09),
(2,2,1,2,0.12),
(3,3,1,3,0.16),
(4,4,1,4,0.19),
(5,5,1,5,0.23),
(6,6,2,1,0.12),
(7,7,2,2,0.19),
(8,8,2,3,0.27),
(9,9,2,4,0.34),
(10,10,2,5,0.41),
(11,11,3,1,0.16),
(12,12,3,2,0.27),
(13,13,3,3,0.37),
(14,14,3,4,0.48),
(15,15,3,5,0.59),
(16,16,4,1,0.19),
(17,17,4,2,0.34),
(18,18,4,3,0.48),
(19,19,4,4,0.63),
(20,20,4,5,0.77),
(21,21,5,1,0.23),
(22,22,5,2,0.41),
(23,23,5,3,0.59),
(24,24,5,4,0.77),
(25,25,5,5,0.95);
insert into `risks`(`ID`,`RiskState`,`RiskID`,`RiskTitle`,`RiskStatement`,`ApproverID`,`OwnerID`,`CreatorID`,`Likelihood`,`Technical`,`Schedule`,`Cost`,`ClosureCriteria`,`CategoryID`,`AssessmentDate`,`CompletionDate`,`ClosureDate`,`Context`) values
(1,'Completed',1,'t','t',1,5,1,5,2,2,5,'t',NULL,'2019-06-14','2020-09-26',NULL,'t'),
(2,'Completed',2,'t','t',2,1,1,5,3,4,2,'test',NULL,'2019-05-14',NULL,NULL,'t'),
insert into `users`(`ID`,`UserID`,`LastName`,`FirstName`,`Title`,`Email`,`Phone`,`Extension`,`Department`) values
(1,1,'Admin','','Admin','a@yz.com','17890','1234',''),
(2,2,'Last','First','Engineer','a@yz.com','123890','1234','Supplier');
CREATE FUNCTION Consequence(technical int, sched int, cost int, consequence int) RETURNS int
BEGIN
select GREATEST(technical, sched, cost) into consequence;
return consequence;
END;
CREATE FUNCTION CurrentRiskEventID(riskidentifier int, eid int) RETURNS int
BEGIN
select MAX(e.EventID) into eid
FROM riskevents e
WHERE e.eventstatus not in('Open')
AND e.riskid = riskidentifier;
return riskeventid;
END;
CREATE FUNCTION CurrentConsequence(riskidentifier int, currentconsequence int) RETURNS int
BEGIN
SELECT coalesce(
(SELECT GREATEST(actualtechnical, actualschedule, actualcost)
FROM riskevents
WHERE id = CurrentRiskEventID(riskidentifier, 0)
and actualtechnical is not null
ANDactualschedule is not null
andactualschedule is not null),
(SELECT greatest(technical, schedule, cost)
from risks
Where riskid = riskidentifier)
) into currentconsequence;
return currentconsequence;
END;
CREATE FUNCTION CurrentLikelihood(riskidentifier int, currentlikelihood int) RETURNS int
BEGIN
SELECT coalesce(
(SELECT actuallikelihood
FROM riskevents
WHERE id = CurrentRiskEventID(riskidentifier, 0)),
(SELECT r.likelihood
FROM risks r
WHERE r.riskid = riskidentifier)) into currentlikelihood;
return currentlikelihood;
END;
CREATE FUNCTION CurrentRiskLevel(riskidentifier int, currentrisklevel int) RETURNS int
BEGIN
select RiskLevel(CurrentRiskValue(riskidentifier, 0), '') into currentrisklevel;
return currentrisklevel;
END;
CREATE FUNCTION CurrentRiskValue(riskidentifier int, currentriskvalue int) RETURNS int
BEGIN
SELECT RiskValue(CurrentLikelihood(riskidentifier, 0), CurrentConsequence(riskidentifier, 0), 0) into currentriskvalue;
return currentriskvalue;
END;
CREATE FUNCTION GetRiskUserID(riskusertype VARCHAR(25), riskidentifier int, riskuserid int) RETURNS int
BEGIN
SELECT COALESCE(userres.userid, 0) into riskuserid FROM
(
SELECT r.creatorid, r.ownerid, r.approverid, u.userid
FROM risks r, users u
WHERE r.riskid = (select riskidentifier) and
(
((select riskusertype) = 'Creator' AND u.userid = r.creatorid) OR
((select riskusertype) = 'Approver' AND u.userid = r.approverid) OR
((select riskusertype) = 'Owner' AND u.userid = r.ownerid)
)
) userres;
RETURN riskuserid;
END;
CREATE FUNCTION GetRiskUserLastOrFirstName(riskuserid int, riskid int, whichname char(25), firstorlastname char(25)) RETURNS char(25) CHARSET utf8 COLLATE utf8_unicode_ci
BEGIN
SELECT (case
when whichname = 'Last' then u.LastName
WHEN whichname = 'First' THEN u.FirstName
end)
into firstorlastname
FROM users u,risks r
WHERE u.UserID = riskuserid
AND r.RiskID = riskid;
return firstorlastname;
END;
CREATE FUNCTION LatestEventDate(riskidentifier int, riskassessmentdate date, latestdate date) RETURNS date
BEGIN
SELECT COALESCE(
(SELECT ActualDate FROM riskevents evt WHERE evt.eventid = CurrentRiskEventID(riskidentifier, 0) and evt.riskid = riskidentifier),
(SELECT riskassessmentdate)) into latestdate;
return latestdate;
END;
CREATE FUNCTION RiskLevel(riskvalue int, risklevel varchar(4)) RETURNS varchar(4)
begin
SELECT
CASE
WHEN riskvalue >= levels.riskhigh*100 THEN 'High'
WHEN riskvalue >= levels.riskmedium*100 THEN 'Med'
ELSE 'Low'
ENd as cat into risklevel
FROM risklevels levels;
return risklevel;
END;
CREATE FUNCTION RiskValue(likelihood int, consequence int, riskvalue int) RETURNS int
BEGIN
SELECT m.level*100 INTO riskvalue FROM riskmatrixthresholds m WHERE m.likelihood = likelihood AND m.consequence = consequence;
RETURN riskvalue;
END;
注意：SQL 是一种 声明式 语言，而不是 过程式 语言。你告诉它你想要什么，而不是如何得到它。您对函数等的使用是过程性的。
如何让这个应用程序更快？
首先，使用最新版本的MySQL（8+，或MariaDB 10.4+）。更高版本变得更快。
其次，您提出了使用“由函数组成的子查询”的要求。这意味着您可能对性能无能为力。
为什么不呢？隐藏在函数中的子查询是所谓的依赖子查询。那些表现不佳。而且因为它们被埋没了 MySQL 的查询规划器无法做任何有用的事情来优化它们。
重构您的查询以避免使用具有 SELECT 操作的函数将使查询规划器能够了解您的整体查询。这将使它有机会优化事物。您可以将它们替换为视图。
并且不要使用 SELECT tablea, tableb 语法。自 1992 年以来就已经过时了。使用
SELECT tablea JOIN tableb ON tablea.joincolumn = tableb.joincolumn.
我会为您提供更多建议，但我无法弄清楚您的意图。
在 CurrentLikelihood() 和 CurrentConsequence() 中应用以下更改将总查询执行时间减少到 exec 0.070 秒，总计 0.082 秒。
旧的当前可能性查询（产生缓慢且不正确的输出）
SELECT coalesce(
(SELECT actuallikelihood
FROM riskevents
WHERE id = CurrentRiskEventID(riskidentifier, 0)),
(SELECT r.likelihood
FROM risks r
WHERE r.riskid = riskidentifier)) into currentlikelihood;
return currentlikelihood;
工作电流可能性查询
SELECT actuallikelihood INTO currentlikelihood
FROM riskevents
WHERE eventid = CurrentRiskEventID(riskidentifier)
AND riskid = riskidentifier;
旧的 CurrentConsequence 查询（生成缓慢且不正确的输出）
SELECT coalesce(
(SELECT GREATEST(actualtechnical, actualschedule, actualcost)
FROM riskevents
WHERE id = CurrentRiskEventID(riskidentifier, 0)
and actualtechnical is not null
and actualschedule is not null),
(SELECT greatest(technical, schedule, cost)
from risks
Where riskid = riskidentifier)
) into currentconsequence;
工作电流结果查询
SELECT GREATEST(actualtechnical, actualschedule, actualcost) INTO currentconsequence
FROM riskevents
WHERE eventid = CurrentRiskEventID(riskidentifier)
AND riskid = riskidentifier;
旧 CurrentRiskEventID() 查询
select MAX(e.EventID) into currentriskeventid
FROM riskevents e
WHERE e.eventstatus not in('Open')
AND e.riskid = riskidentifier;
修改后的 GetRiskEventID() 函数
SELECT MAX(e.EventID) INTO currentriskeventid
FROM riskevents e
WHERE e.riskid = riskidentifier AND
(e.eventstatus != 'Open'
OR
(e.EventID = 0 AND e.eventstatus = 'Open'));