ean 13 check digit calculator c# Part III in Visual C#.NET

Draw EAN13 in Visual C#.NET Part III

The compatibility level of a database specifies the SQL Server version compatibility and can be set to SQL Server 7.0 (70), SQL Server 2000 (80), or SQL Server 2005 (90). When set to a value other than SQL Server 2005 (90), the compatibility level makes the database behavior compatible with that version of SQL Server. It is highly recommended that you use the SQL Server 2005 (90) compatibility level. The other compatibility levels are provided primarily to help quickly address upgrade time incompatibilities and provide you with time to work through the issues. The compatibility level cannot be set using the ALTER DATABASE command; you need to use the sp_dbcmptlevel stored procedure instead. For example, the following command sets the database compatibility level for the TestDB database to SQL Server 2000.

sp_dbcmptlevel TestDB, 80 ;

For a detailed list of differences between the different compatibility levels, you may want to refer to the Behavioral Differences Between Level 60 or 65 and Level 70, 80, or 90 section in the sp_dbcmptlevel help topic in SQL Server Books Online.

Auto Close (AUTO_CLOSE)

You can use this option to control whether the database will be automatically closed when not in use. When this option is set to TRUE in SQL Server Management Studio, or to ON when using the ALTER DATABASE command, SQL Server closes the database whenever the last user disconnects from it, freeing up the associated resources. When a user tries to use the database again, the database is reopened. The closing and reopening process is completely automatic and transparent. Best Practices

Usually a SQL Server instance has only a few user databases, but it is possible for it to have several hundred databases, for example, being a hosting provider that hosts many small user databases on a single server instance. For database instances with hundreds of databases that are infrequently accessed, it is recommended to set the database s AUTO_CLOSE option to TRUE. Setting this option forces the database to be closed when all the database processes complete and all users disconnect from the database, thereby freeing up server resources. The AUTO_CLOSE option is not recommended for frequently accessed databases.

Auto Create Statistics (AUTO_CREATE_STATISTICS)

Accurate optimization of some queries often requires column statistics on specific columns that may not already have statistics created on them. Setting the Auto Create Statistics option to TRUE in SQL Server Management Studio, or to ON when using the

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ALTER DATABASE command, permits SQL Server to create statistic on a table columns automatically as needed. You should always leave this option set to TRUE unless you have a very good reason to turn it off. Note

Statistics that are automatically generated by SQL Server always have the prefix _WA_Sys_ and end in a hexadecimal number. For example, _WA_Sys_ProcessID_2CD08213 is an auto-created statistic on column ProcessID. You can view all auto- and manually created statistics using the sp_autostats <table name> command. For example, you can check on the statistics for the Persons table in the AdventureWorks database using the command sp_autostats 'Person.Address'.

Auto Shrink (AUTO_SHRINK)

You can use this option to control whether the database files will be automatically shrunk. When this option is set to TRUE in SQL Server Management Studio, or to ON when using the ALTER DATABASE command, the database data and log files are shrunk when more than 25 percent of the file contains unused space. The files are shrunk to a size where 25 percent of the file is unused space, or to the size of the file when it was created, whichever is larger. In most cases it is advisable to leave this option set to FALSE.

Auto Update Statistics (AUTO_UPDATE_STATISTICS)

You can use this option to control whether statistics will be updated automatically. SQL Server uses a cost-based optimizer that is extremely sensitive to the accuracy of the statistical information available to it. To ensure that relatively accurate statistics are always available, it employs the auto update statistics mechanism. You should always leave the Auto Update Statistics database option set to TRUE for all user databases. If there is an exceptional situation where you believe that this option needs to be disabled for a particular table, you should disable it only for the particular table using the sp_autostats command. Disabling this option at the database level can have some nasty long-term performance implications.