Databases - Relational databases
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Author: Meg Jones
Databases are used in many different ways and therefore providing high quality data for every type of user is a difficult and challenging task. However, there are a number of requirements in common, which are discussed in further detail below. Databases are generally much bigger than the catalogue, however - the largest ones index thousands of journals. The wide scope of databases makes them very useful for tracking down the material you need, but it can also be frustrating if you find that your searches are returning a large volume of irrelevant material. Databases are frequently combined into larger collections of databases, (also called databases,) often several times. An individual magazine or database may exist within several databases and several collections.
Databases are created to manage distinct sets or types of information . By searching a specialized database, you can expect a certain kind of result. Databases are probably one of the most common uses of computers, and are available on just about every type of computer. Databases are not created automatically on account creation, but can be requested from the Unix Committee by email or in person. Currently new databases are available on one of our MySQL 5.0 servers and our PostgreSQL 8.3 server.
Relational databases use tables to store information. The standard fields and records are represented as columns (fields) and rows (records) in a table. Relational databases simply absorbed their best features and continued to rule. Simple database features like triggers and stored procedures gave way to more sophisticated technologies like replication, online backup, and cluster support. Relational databases are far more flexible (though harder to design and maintain) than what are known as flat file databases, which contain a single table of data.
Relational databases are a proven technology that can handle large applications with minimum of headaches. A web application, written in a language like Java, Perl or PHP, provides a bridge between the two.
SQL is currently used on practically all relational databases. Relational databases are extremely easy to customize to fit almost any kind of data storage. SQL Server internally reserves preallocated space in database files for rollbacks. It is possible on compressed volumes to receive an Out of Space error on preallocated files, interfering with successful recovery.
Databases, on the other hand, can set and hold mutiple locks at the same time on the different level of the physical data structure. How locks are set, last is determined by the database engine locking scheme based on the submitted SQL or transactions by the users. Database software provides a computer program--a structure--for developing a file of information on any topic. Such a program enables the teacher or students to create custom-made databases for classroom use. Databases that are not available from home are indicated with a red icon.
Database owners should think about the extent to which they need to make their database users aware of the fact that patent rights may restrict the use that can be made of the factual information contained in a database. Databases can be listed for each topic along with brief descriptions of their content, topics covered, and web sites which offer guides to using the various databases. For general information, a good place to start is with the fulltext Magazine & Periodicals , or Newspapers , or Current Events topics. Database administration processes are cyclical. When solutions have been executed to correct problems that were reported by the analysis, the cycle begins anew.
Data in databases should include all data that is needed for a reinterpretation of the result. Data bases should include metadata that describe the sample, sample handling and the measurement techniques. Database records typically provide publication information about the author(s), title, publisher, publication date, and subject of a source.
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