The following are some frequently asked questions in the SAP Basis / Technical arena

How can I lock a transaction?
Use transaction SM01.
Look for the transaction you want and then check the "Locked" box.

Why should I lock a transaction?
Because some transactions are "dangerous" and a user without the proper training may accidentally corrupt or destroy the system.

 How can I see what users are currently logged on an R/3 system?
Use either transaction SM04 or AL08.

What is the fastest way to log off in SAPGUI?
Type /NEX at the command field.
Notice that this transaction exists without asking for confirmation. Save your work before using it.

How do I find information about transaction codes?
Run transaction SE93 to create, edit or display transactions.

How do I check for errors in R/3?
Run transaction SM21 for read the System Log.

How do I logon to a SAPServX FTP server?
User = ftp; password = ftp.

Do I always have to use the new visual design in SAPGUI (EnjoySAP)?
No. In fact, you can switch to the SAPGUI "light". Simply use the "SAP Configuration" program in Control Panel.

How do I log on to SAPNet?
Use transaction OSS1 to log on to SAPNet R/3 FrontEnd. To log on to SAPNet R/3 Web visit: https://service.sap.com.

Can I copy all users from client to another?
Yes. Use copy profile SAP_USER.

Can I script the starting and stopping of R/3?
Definitely. You can use the SAPSTART, SAPSRVKILL and SAPNTWAITFORHALT executables.

Where can I get a list of all transaction codes in SAP?
The following tables hold all SAP transactions:
Table TSTC stores all transaction codes and their respective ABAP program.
Table TSTCT stores the text (or description) for each transaction.
Table THSTC has also documentation for all transaction. It is a copy of TSTCT.
Table TSTCP stores the possible parameters for each transaction.

Where can I get a list of all tables in SAP?
Table DD02L stores all tables in SAP.

How can I hide a client from the users?
There is no way to actually hide a client but there is a workaround: delete the entry in table T000 via SCC4. This way, nobody will able to log on to it. To "unhide" it, simply re-create the entry via SCC4.

How can I lock a client?
You can use one of these two: 1) delete the entry in table T000 via SCC4; 2) run tp locksys at the OS level. 

How can I determine the size of a client?
You can run a local client copy in "test" mode.

How do I backup a database?
You can create a maintenance plan or use the "backup database" SQL statement in Query Analyzer or OSQL.
Within SAP, you can use DB13.

What is the transaction to access the language utility?
Transaction SMLT takes you to the Language Transport Utility.

How can I see all the available icons in SAP?
Execute transaction BIBS and select Elements -> Icon Overview.
You can use the code that appears on the last column in order to put icons in system messages (SM02).

In what tables can I find P.O. documents?
Purchase Orders are stored in table EKPO and field EBELN.
You can also find them in these two tables:
EKK0 (Purchasing Document Header)
EKET (Scheduling Agreement Schedule Lines)

ABAP Query does not seem to work, what should I do?
It could be that you need to execute report RSAQUM40 to set the release flag. See SAP note 92124 for more information.

What happens if I start a dialog instance but the database and SAP services are down on the central instance?
The SAP<SID>_xx and SAPOSCOL services will start.
However, the work processes will end soon after being started.

What happens if I start a dialog instance but only the database services are up on the central instance?
The SAP services will start and so will the work processes. However, because the message server is down on the central instance users will get the message "No logon possible (no hardware ID received by message server) when trying to log on. No user logins will work. The "Process List" in the SAP MMC will stay in yellow.

If using Single Sign-On, do the passwords in SAP and Windows have to match?
No. Only the user IDs must match for single-on to work. 

Can I import transports between different R/3 releases?
Read the technical and logical problems SAP reports when doing transports between different R/3 releases.
SAP Notes 126776 and 330267.

I lost the password for SAP*. What can I do?
You can delete the record for SAP* in table USR02 as follows:
delete USR02 where BNAME="SAP*" and MANDT='XXX'
Replace 'XXX' for a valid client number.

Can SAP be installed on FAT or FAT32 partitions?
No. SAP needs to be installed on NTFS partitions only.

How can I quickly check if the passwords for the accounts SAP*, DDIC, SAPCPIC and EarlyWatch are not the default ones?
Run SE38 and execute report RSUSR003.

Can I copy just data from client to another?
No. There is no copy profile that allows you to copy just data.
For this you need to configure and use ALE or buy a third-party program that has this type of functionality.

Can Query Analyzer tell me if there is insufficient disk space to restore a database?
Yes. It will display message (Msg) 3257 indicating that there is not enough disk space to perform the restore.