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)
(