SQL Turning 是Quest公司出品的Quest Central软件中的一个工具。Quest Central是一款集成化、图形化、跨平台的数据库管理解决方案，可以同时管理 Oracle、DB2 和 SQL server 数据库。 一、SQL Tuning for SQL Server简介 SQL语句的优化对发挥数据库的最佳性

　　SQL Turning 是Quest公司出品的Quest Central软件中的一个工具。Quest Central是一款集成化、图形化、跨平台的数据库管理解决方案，可以同时管理 Oracle、DB2 和 SQL server 数据库。

　　一、SQL Tuning for SQL Server简介

　　SQL语句的优化对发挥数据库的最佳性能非常关键。然而不幸的是，应用优化通常由于时间和资源的因素而被忽略。SQL Tuning (SQL优化)模块可以对比和评测特定应用中SQL语句的运行性能，提出智能化的优化建议，帮助用户改善应用的响应时间。SQL优化模块具有非介入式SQL采集、自动优化和专家建议等功能，全面改善SQL优化工作。

　　二、SQL Tuning for SQL Server的使用

　　1、打开Quest Database Management Solutions弹出窗口如图1所示

　　图1

　　2、在红色标记处打开SQL Tuning 优化SQL

　　(1)建立连接。

　　在Quest Central主界面上的“Database”树上选择“SQL Server”，然后在下方出现的“Tools”框中选择“SQL Tuning”选项，打开“Lanch SQL Tuning for SQL Server Connections”对话框(图2、图3)。我们在这里建立数据库服务器的连接，，以后的分析工作都会在它上面完成。

　　图2 “建立连接”对话框

　　图3

　　双击“New Connection”图标，在弹出窗口中输入数据库的信息，单击“OK”，然后单击“Connect”即可。

　　(2)分析原始SQL语句 ，在单击“Connect”后将弹出一个新窗口，如图4

　　图4

　　在打开窗口的“Oriangal SQL”文本框内输入需要分析的原始SQL语句，红色标记处选择对应的数据库名，SQL语句代码如下：

　　图5 分析原始SQL语句

　　原始SQL语句

　　然后点击工具栏上的“Execute”按钮，执行原始的SQL语句，SQL Tuning会自动分析SQL的执行计划，并把分析结果显示到界面上(图5)。

　　(3)优化SQL。

　　现在我们点击工具栏上的“Optimize Statement”按钮,让SQL Tuning开始优化SQL，完成后，可以看到SQL Tuning产生了19条与原始SQL等价的优化方案(图6)。

　　图6 SQL优化方案

　　(4)获得最优SQL。

　　接下来，我们来执行上面产生的优化方案，以选出性能最佳的等效SQL语句。在列表中选择需要执行的优化方案(默认已全部选中)，然后点击工具栏上的“Execute”按钮旁边的下拉菜单，选择“Execute Selected”。等到所有SQL运行完成后,点击界面左方的“Tuning Resolution”按钮，

　　可以看到最优的SQL已经出来啦，运行时间竟然可以提高21%!(图7)

　　图7 “Tuning Resolution”界面

　　最优的SQL语句如下：

　　5)学习书写专家级的SQL语句 。

　　优化后的SQL语句

　　SELECT dbo.Person_BasicInfo.*,

　　dbo.Graduater_GraduaterRegist.RegistNO AS RegistNO,

　　dbo.Graduater_GraduaterRegist.RegistTime AS BaoDaoTime,

　　dbo.Graduater_GraduaterRegist.RegistMan AS RegistMan,

　　dbo.Graduater_Business.ComeFrom AS ComeFrom,

　　dbo.Graduater_Business.Code AS Code,

　　dbo.Graduater_Business.Status AS Status,

　　dbo.Graduater_Business.ApproveResult AS ApproveResult,

　　dbo.Graduater_Business.NewCorp AS NewCorp,

　　dbo.Graduater_Business.CommendNumber AS CommendNumber,

　　dbo.Graduater_Business.EmployStatus AS EmployStatus,

　　dbo.Graduater_Business.NewCommendTime AS NewCommendTime,

　　dbo.Graduater_Business.GetSource AS GetSource,

　　dbo.Graduater_Business.EmployTime AS EmployTime,

　　dbo.Graduater_Business.Job AS Job,

　　dbo.Graduater_Business.FillMan AS FillMan,

　　dbo.Graduater_Business.FillTime AS FillTime,

　　dbo.Graduater_Business.IsCommendOK AS IsCommendOK,

　　dbo.Graduater_Business.ApproveUser AS ApproveUser,

　　dbo.Graduater_Business.ApproveTime AS ApproveTime,

　　dbo.Graduater_Business.RegistTime AS RegistTime,

　　dbo.Graduater_Business.EmployCorp AS EmployCorp,

　　dbo.Graduater_Business.JobRemark AS JobRemark,

　　CASE WHEN dbo.Graduater_Business.ComeFrom = 'WS' THEN '网上登记'

　　WHEN dbo.Graduater_Business.ComeFrom = 'HP' THEN '华普大厦'

　　WHEN dbo.Graduater_Business.ComeFrom = 'JD' THEN '精典大厦'

　　WHEN dbo.Graduater_Business.ComeFrom = 'MC' THEN '赛马场'

　　WHEN ComeFrom = 'ZX' THEN '高指中心' END AS ComeFromName,

　　dbo.Person_Contact.Address AS Address,

　　dbo.Person_Contact.Zip AS Zip,

　　dbo.Person_Contact.Telephone AS Telephone,

　　dbo.Person_Contact.Mobile AS Mobile,

　　dbo.Person_Contact.Email AS Email,

　　dbo.Person_Contact.IM AS IM,

　　dbo.Person_Skill.ForeignLanguage AS ForeignLanguage,

　　dbo.Person_Skill.ForeignLanguageLevel AS ForeignLanguageLevel,

　　dbo.Person_Skill.CantoneseLevel AS CantoneseLevel,

　　dbo.Person_Skill.MandarinLevel AS MandarinLevel,

　　dbo.Person_Skill.Language AS Language,

　　dbo.Person_Skill.TechnicalTitle AS TechnicalTitle,

　　dbo.Person_Skill.ComputerLevel AS ComputerLevel,

　　dbo.Person_EmployPurpose.JobType AS JobType,

　　dbo.Person_EmployPurpose.Vocation AS Vocation,

　　dbo.Person_EmployPurpose.JobPlace AS JobPlace,

　　dbo.Person_EmployPurpose.Salary AS Salary,

　　dbo.Person_EmployPurpose.OnJobDate AS OnJobDate,

　　dbo.Person_EmployPurpose.CorpType AS CorpType,

　　dbo.Person_EmployPurpose.Job AS RequireJob,

　　YEAR(GETDATE()) - YEAR(dbo.Person_BasicInfo.Birthday) AS Age,

　　dbo.Graduater_Business.EmployType AS EmployType,

　　dbo.Graduater_Business.EmployTypeCode AS EmployTypeCode,

　　dbo.Graduater_Business.EmployCorpType AS EmployCorpType,

　　CASE WHEN dbo.Graduater_Business.PrintStatus = '已打印' THEN '已打印'

　　ELSE '未打印' END AS PrintStatus,

　　dbo.Graduater_Business.PrintTime AS PrintTime,

　　CASE WHEN dbo.Graduater_Business.EmployStatus = '是' THEN '已就业'

　　ELSE '未就业' END AS EmployStatusView

　　FROM dbo.Person_BasicInfo

　　INNER JOIN dbo.Graduater_Business

　　ON dbo.Person_BasicInfo.PersonID = dbo.Graduater_Business.PersonID

　　LEFT OUTER JOIN dbo.Graduater_GraduaterRegist

　　ON dbo.Graduater_Business.GradBusinessID = dbo.Graduater_GraduaterRegist.GraduaterGUID

　　INNER JOIN dbo.Person_Contact

　　ON dbo.Person_BasicInfo.PersonID = dbo.Person_Contact.PersonID

　　INNER JOIN dbo.Person_Skill

　　ON dbo.Person_BasicInfo.PersonID = dbo.Person_Skill.PersonID

　　INNER JOIN dbo.Person_EmployPurpose

　　ON dbo.Person_BasicInfo.PersonID = dbo.Person_EmployPurpose.PersonID

　　OPTION (FORCE ORDER)

　　(