DATABASE BACKUPS, RECOVERY, AND MAINTENANCE in C#

Generation Data Matrix barcode in C# DATABASE BACKUPS, RECOVERY, AND MAINTENANCE

This article describes how to use .NET Remoting for sharing the clipboard of one computer with other computers. http://www.codeproject.com/dotnet/clipsend.asp

Figure 3-7. SQLcmd command-line options Each of the items in the list that is displayed is called a command-line switch. These switches are passed into the SQLcmd utility when it is launched and provide it some instructions on how to behave. There are too many to look at here, and not all switches are relevant; however, Table 3-2 outlines the main switches and their uses. Table 3-2. SQLcmd Most Common Switches

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Sum(index range scan * 1.4) blocks for 20% scattered rows blocks for 80% packed rows 41 * 1.4 * 2 + 80 + 5.7

Burn audio or CD-R/RW data discs (the latter usually based on an ISO image; see mkisofs)

Note Unlike stored procedures, you cannot manually make a trigger run, you cannot use parameters with

Two-way data binding works in most cases, however, it does not work with Style or Effect properties nor does it work with arguments for RemoteObject or the request property for HttpService, RemoteObject, or WebService. The reason that the two-way data binding will fail is that both the source and target properties must be bindable as well as readable and writable to allow two-way data binding.

Figure 7-29. Shrinking the database 10. Click Next to bring up the Define Reorganize Index Tag screen, shown in Figure 7-30. As data is added, modified, and deleted, indexes, like tables, can also require reorganizing, which you can do through this screen. Again, this is like a hard drive defrag where there are gaps or data out of order, and by reorganizing indexes you will ensure that SQL Server will be able to access the data as fast as possible. This option, which should be completed at least weekly for a high data modification system, will only move index pages.

Now that the database is up and built and the tables are there, it really is time to start considering a whole database maintenance plan before data is entered. This will cover database corruption through to inadvertent errors in development. Even though corruption is rare in SQL Server, it can be caused when the SQL Server loses power abruptly, for example, or through hardware issues such as motherboard failure or someone removing the network cable. There are many areas to building a maintenance plan, and this section covers a lot of them. One or two areas are only touched on as they are quite advanced and will not be covered in this book. You will still need a little background so that you can see how crucial this area is, and we can move on to those more advanced areas a bit later on. A single maintenance plan can be built for one database or several databases. A single plan can be set up for system databases and all user databases by selecting those options at the start of the Database Maintenance Wizard. However, it is recommended that you create a plan for all system databases, but have a separate maintenance plan for each separate user database. The logic behind this is that each user database will have its own needs, its own overnight routines, and even its own people for callout when things go wrong. Even if you are a one-man band, each user database should still have a maintenance plan. Therefore, in keeping with this, only the ApressFinancial database will be selected.

backup device, or that no errors occurred when writing the data. A situation such as this is unusual, but there will be times that it does happen. Do you trust that those times will occur when you will not need a backup I suggest this is something you just cannot and should not rely on. Therefore, although it will increase the amount of time the backup takes, it is good to choose one of the two options in this section. The two options are to allow a verification of the backup where SQL Server compares what has been backed up with what it expects to have been backed up, and the second option allows for checksum processing whereby SQL Server performs a mathematical calculation on the data to back up, which will generate a checksum that can then be compared once the data has been transmitted from SQL Server to the backup device. If you select the second option, you can also specify whether to continue if you get a checksum error. If you are doing a transaction log backup, the next area of the dialog box would be enabled. You can logically shrink the transaction log by removing all entries that have just been backed up by selecting the first option, Truncate the Transaction Log. To save processing time, the physical transaction log is not shrunk. The second option, Back Up the Tail of the Log, is used when there has been some sort of database corruption. If you wish to back up transaction log records that have not been backed up prior to performing a restore to correct the corruption, then you would use this option. To clarify, a database becomes corrupt, and you need to be able to restore up to the last backup, then add all the transactions that have occurred since the last backup. By executing a backup of the tail of the log, you can restore the database and then use this tail log backup to add the missing transactions. The final area of the dialog box is available if you are using tapes as your backup medium. You can eject the tape once the backup has finished. This is a useful option as the computer operators would know to remove the tape for dispatch to the safe backup area. The second option, which specifies a rewind, is useful for full backups. On differential backups, however, SQL Server would be halted when running the next backup while the tape device got to the right place on the tape to continue the backup. Clicking OK will then start the backup. Once the backup is finished you should see the dialog box shown in Figure 7-4.

In this example of conditional looping, the second input parameter of the logical Equal functoid is a hard-coded constant set to True. In real-world scenarios, it may not be ideal for this value to be hardcoded. You may prefer to have it driven off a configurable value. Several alternatives exist: Implement a Scripting functoid to the map, which passes the name of a configuration value to an external assembly. This external assembly would then handle the lookup of the actual configuration value.