List of commands that you can run off from the Run Command Prompt

Here is a list of commands that you can run off from the Run Command Prompt:

Program Run Command

Accessibility Controls = access.cpl
Accessibility Wizard = accwiz
Add Hardware Wizard = hdwwiz.cpl
Add/Remove Programs = appwiz.cpl
Administrative Tools = control admintools
Adobe Acrobat ( if installed ) = acrobat
Adobe Distiller ( if installed ) = acrodist
Adobe ImageReady ( if installed ) = imageready
Adobe Photoshop ( if installed ) = photoshop
Automatic Updates = wuaucpl.cpl
Basic Media Player = mplay32
Bluetooth Transfer Wizard = fsquirt

Calculator = calc
Ccleaner ( if installed ) = ccleaner
C: Drive = c:
Certificate Manager = cdrtmgr.msc
Character Map = charmap
Check Disk Utility = chkdsk
Clipboard Viewer = clipbrd
Command Prompt = cmd
Command Prompt = command
Component Services = dcomcnfg
Computer Management = compmgmt.msc
Compare Files = comp
Control Panel = control
Create a shared folder Wizard = shrpubw

Date and Time Properties = timedate.cpl
DDE Shares = ddeshare
Device Manager = devmgmt.msc
Direct X Control Panel ( if installed ) = directx.cpl
Direct X Troubleshooter = dxdiag
Disk Cleanup Utility = cleanmgr
Disk Defragment = dfrg.msc
Disk Partition Manager = diskmgmt.msc
Display Properties = control desktop
Display Properties = desk.cpl
Display Properties (w/Appearance Tab Preselected ) = control color
Dr. Watson System Troubleshooting Utility = drwtsn32
Driver Verifier Utility = verifier

Ethereal ( if installed ) = ethereal
Event Viewer = eventvwr.msc
Files and Settings Transfer Tool = migwiz
File Signature Verification Tool = sigverif
Findfast = findfast.cpl
Firefox = firefox
Folders Properties = control folders
Fonts = fonts
Fonts Folder = fonts
Free Cell Card Game = freecell

Game Controllers = joy.cpl
Group Policy Editor ( xp pro ) = gpedit.msc
Hearts Card Game = mshearts
Help and Support = helpctr
Hyperterminal = hypertrm
Hotline Client = hotlineclient

Iexpress Wizard = iexpress
Indexing Service = ciadv.msc
Internet Connection Wizard = icwonn1
Internet Properties = inetcpl.cpl
Internet Setup Wizard = inetwiz
IP Configuration (Display Connection Configuration) = ipconfig /all
IP Configuration (Display DNS Cache Contents) = ipconfig /displaydns
IP Configuration (Delete DNS Cache Contents) = ipconfig /flushdns
IP Configuration (Release All Connections) = ipconfig /release
IP Configuration (Renew All Connections) = ipconfig /renew
IP Configuration (Refreshes DHCP & Re-Registers DNS) = ipconfig /registerdns
IP Configuration (Display DHCP Class ID) = ipconfig /showclassid
IP Configuration (Modifies DHCP Class ID) = ipconfig /setclassid

Java Control Panel ( if installed ) = jpicpl32.cpl
Java Control Panel ( if installed ) = javaws
Keyboard Properties = control keyboard

Local Security Settings = secpol.msc
Local Users and Groups = lusrmgr.msc
Logs You Out of Windows = logoff

Malicious Software Removal Tool = mrt
Microsoft Access ( if installed ) = access.cpl
Microsoft Chat = winchat
Microsoft Excel ( if installed ) = excel
Microsoft Diskpart = diskpart
Microsoft Frontpage ( if installed ) = frontpg
Microsoft Movie Maker = moviemk
Microsoft Management Console = mmc
Microsoft Narrator = narrator
Microsoft Paint = mspaint
Microsoft Powerpoint = powerpnt
Microsoft Word ( if installed ) = winword
Microsoft Syncronization Tool = mobsync
Minesweeper Game = winmine
Mouse Properties = control mouse
Mouse Properties = main.cpl
MS-Dos Editor = edit
MS-Dos FTP = ftp

Nero ( if installed ) = nero
Netmeeting = conf
Network Connections = control netconnections
Network Connections = ncpa.cpl
Network Setup Wizard = netsetup.cpl
Notepad = notepad
Nview Desktop Manager ( if installed ) = nvtuicpl.cpl

Object Packager = packager
ODBC Data Source Administrator = odbccp32
ODBC Data Source Administrator = odbccp32.cpl
On Screen Keyboard = osk
Opens AC3 Filter ( if installed ) = ac3filter.cpl
Outlook Express = msimn

Paint = pbrush
Password Properties = password.cpl
Performance Monitor = perfmon.msc
Performance Monitor = perfmon
Phone and Modem Options = telephon.cpl
Phone Dialer = dialer
Pinball Game = pinball
Power Configuration = powercfg.cpl
Printers and Faxes = control printers
Printers Folder = printers
Private Characters Editor = eudcedit

Quicktime ( if installed ) = quicktime.cpl
Quicktime Player ( if installed ) = quicktimeplayer

Real Player ( if installed ) = realplay
Regional Settings = intl.cpl
Registry Editor = regedit
Registry Editor = regedit32
Remote Access Phonebook = rasphone
Remote Desktop = mstsc
Removable Storage = ntmsmgr.msc
Removable Storage Operator Requests = ntmsoprq.msc
Resultant Set of Policy ( xp pro ) = rsop.msc

Scanners and Cameras = sticpl.cpl
Scheduled Tasks = control schedtasks
Security Center = wscui.cpl
Services = services.msc
Shared Folders = fsmgmt.msc
Sharing Session = rtcshare
Shuts Down Windows = shutdown
Sounds Recorder = sndrec32
Sounds and Audio = mmsys.cpl
Spider Solitare Card Game = spider
SQL Client Configuration = clicongf
System Configuration Editor = sysedit
System Configuration Utility = msconfig
System File Checker Utility ( Scan Immediately ) = sfc /scannow
System File Checker Utility ( Scan Once At Next Boot ) = sfc /scanonce
System File Checker Utility ( Scan On Every Boot ) = sfc /scanboot
System File Checker Utility ( Return to Default Settings) = sfc /revert
System File Checker Utility ( Purge File Cache ) = sfc /purgecache
System File Checker Utility ( Set Cache Size to Size x ) = sfc /cachesize=x
System Information = msinfo32
System Properties = sysdm.cpl

Task Manager = taskmgr
TCP Tester = tcptest
Telnet Client = telnet
Tweak UI ( if installed ) = tweakui
User Account Management = nusrmgr.cpl
Utility Manager = utilman

Volume Serial Number for C: = label
Volume Control = sndvol32
Windows Address Book = wab
Windows Address Book Import Utility = wabmig
Windows Backup Utility ( if installed ) = ntbackup
Windows Explorer = explorer
Windows Firewall = firewall.cpl
Windows Installer Details = msiexec
Windows Magnifier = magnify

Windows Management Infrastructure = wmimgmt.msc
Windows Media Player = wmplayer
Windows Messenger = msnsgs
Windows Picture Import Wizard (Need camera connected) = wiaacmgr
Windows System Security Tool = syskey
Windows Script host settings = wscript
Widnows Update Launches = wupdmgr
Windows Version ( shows your windows version ) = winver
Windows XP Tour Wizard = tourstart
Wordpad = write
Zoom Utility = igfxzoom

Left outer join vs NOT EXISTS in SQL

And to wrap up the miniseries on IN, EXISTS and JOIN, a look at NOT EXISTS and LEFT OUTER JOIN for finding non-matching rows.

For previous parts, see

• In vs Exists
• In vs Inner Join
• Not in vs Not Exists

I’m looking at NOT EXISTS and LEFT OUTER JOIN, as opposed to NOT IN and LEFT OUTER JOIN, because, as shown in the previous part of this series, NOT IN behaves badly in the presence of NULLs. Specifically, if there are any NULLs in the result set, NOT IN returns 0 matches.

The LEFT OUTER JOIN, like the NOT EXISTS can handle NULLs in the second result set without automatically returning no matches. It behaves the same regardless of whether the join columns are nullable or not. Seeing as NULL does not equal anything, any rows in the second result set that have NULL for the join column are eliminated by the join and have no further effect on the query.

It is important, when using the LEFT OUTER JOIN … IS NULL, to carefully pick the column used for the IS NULL check. It should either be a non-nullable column (the primary key is a somewhat classical choice) or the join column (as nulls in that will be eliminated by the join)

Onto the tests

The usual test tables…

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CREATE TABLE BigTable ( id INT IDENTITY PRIMARY KEY, SomeColumn char(4) NOT NULL, Filler CHAR(100) ) CREATE TABLE SmallerTable ( id INT IDENTITY PRIMARY KEY, LookupColumn char(4) NOT NULL, SomeArbDate Datetime default getdate() ) INSERT INTO BigTable (SomeColumn) SELECT top 250000 char(65+FLOOR(RAND(a.column_id *5645 + b.object_id)*10)) + char(65+FLOOR(RAND(b.column_id *3784 + b.object_id)*12)) + char(65+FLOOR(RAND(b.column_id *6841 + a.object_id)*12)) + char(65+FLOOR(RAND(a.column_id *7544 + b.object_id)*8)) from master.sys.columns a cross join master.sys.columns b INSERT INTO SmallerTable (LookupColumn) SELECT DISTINCT SomeColumn FROM BigTable TABLESAMPLE (25 PERCENT) -- (3918 row(s) affected)

First without indexes

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-- Query 1 SELECT BigTable.ID, SomeColumn   FROM BigTable LEFT OUTER JOIN SmallerTable ON BigTable.SomeColumn = SmallerTable.LookupColumn   WHERE LookupColumn IS NULL -- Query 2 SELECT ID, SomeColumn FROM BigTable WHERE NOT EXISTS (SELECT LookupColumn FROM SmallerTable WHERE SmallerTable.LookupColumn = BigTable.SomeColumn)

Let’s take a look at the execution plans

The plans are almost the same. There’s an extra filter in the JOIN and the logical join types are different. Why the different joins?

If we look at the execution plan for the NOT EXISTS, the join type is Right Anti-Semi join (a bit of a mouthful). This is a special join type used by the NOT EXISTS and NOT IN and it’s the opposite of the semi-join that I discussed back when I looked at IN and INNER JOIN

An anti-semi join is a partial join. It does not actually join rows in from the second table, it simply checks for, in this case, the absence of matches. That’s why it’s an anti-semi join. A semi-join checks for matches, an anti-semi join does the opposite and checks for the absence of matches.

The extra filter in the LEFT OUTER JOIN query is because the join in that execution plan is a complete right join, i.e. it’s returned matching rows (and possibly duplicates) from the second table. The filter operator is doing the IS NULL filter.

That’s the major difference between these two. When using the LEFT OUTER JOIN … IS NULL technique, SQL can’t tell that you’re only doing a check for nonexistance. Optimiser’s not smart enough (yet). Hence it does the complete join and then filters. The NOT EXISTS filters as part of the join.

Technical discussion done, now how did they actually perform?

– Query 1: LEFT OUTER JOIN
Table ‘Worktable’. Scan count 0, logical reads 0, physical reads 0.
Table ‘BigTable’. Scan count 1, logical reads 3639, physical reads 0.
Table ‘SmallerTable’. Scan count 1, logical reads 15, physical reads 0.

SQL Server Execution Times:
CPU time = 157 ms,  elapsed time = 486 ms.

– Query 2: NOT EXISTS
Table ‘Worktable’. Scan count 0, logical reads 0, physical reads 0.
Table ‘BigTable’. Scan count 1, logical reads 3639, physical reads 0.
Table ‘SmallerTable’. Scan count 1, logical reads 15, physical reads 0.

SQL Server Execution Times:
CPU time = 156 ms,  elapsed time = 358 ms.

Can’t make a big deal out of that.

Now, index on the join columns

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CREATE INDEX idx_BigTable_SomeColumn ON BigTable (SomeColumn) CREATE INDEX idx_SmallerTable_LookupColumn ON SmallerTable (LookupColumn)

and the same queries

With indexes added, the execution plans are even more different. The LEFT OUTER JOIN is still doing the complete outer join with a filter afterwards. It’s interesting to note that it’s still a hash join, even though both inputs are sorted in the order of the join keys.

The Not Exists now has a stream aggregate (because duplicate values are irrelevant for an EXISTS/NOT EXISTS) and an anti-semi join. The join here is no longer hash, it’s now a merge join.

This echoes what I found when looking at IN vs Inner join. When the columns were indexed, the inner join still went for a hash join but the IN changed to a merge join. At the time, I thought it to be a fluke, I’m not so sure any longer. More tests on this are required…

The costing of the plans indicates that the optimiser believes that the LEFT OUTER JOIN form is more expensive. Do the execution stats carry the same conclusion?

– Query 1: LEFT OUTER JOIN
Table ‘Worktable’. Scan count 0, logical reads 0, physical reads 0.
Table ‘BigTable’. Scan count 1, logical reads 342, physical reads 0.
Table ‘SmallerTable’. Scan count 1, logical reads 8, physical reads 0.

SQL Server Execution Times:
CPU time = 172 ms,  elapsed time = 686 ms.

– Query 2: NOT EXISTS
Table ‘BigTable’. Scan count 1, logical reads 342, physical reads 0.
Table ‘SmallerTable’. Scan count 1, logical reads 8, physical reads 0.

SQL Server Execution Times:
CPU time = 78 ms,  elapsed time = 388 ms.

Well, yes, they do.

The reads (ignoring the existence of the worktable for the hash join) are the same. That’s to be expected, both queries executed with a single scan of each index.

The CPU time figures are not. The CPU time of the LEFT OUTER JOIN form is almost twice that of the NOT EXISTS.

In conclusion…

If you need to find rows that don’t have a match in a second table, and the columns are nullable, use NOT EXISTS. If you need to find rows that don’t have a match in a second table, and the columns are not nullable, use NOT EXISTS or NOT IN.

The LEFT OUTER JOIN … IS NULL method is slower when the columns are indexed and it’s perhaps not as clear what’s happening. It’s reasonably clear what a NOT EXISTS predicate does, with LEFT OUTER JOIN it’s not immediately clear that it’s a check for non-matching rows, especially if there are several where clause predicates.

I think that’s about that for this series. I’m going to do one more post summarising all the findings, probably in a week or two.

URL:
http://sqlinthewild.co.za/index.php/2010/03/23/left-outer-join-vs-not-exists/