Tables store data, so they're essential building blocks of any database.
A database should have a separate table for every major subject, such as employee records, customer orders, shipping methods, or suppliers. Data should not be duplicated in multiple tables. Duplicating data is a common error, but it's easy to avoid if you structure your tables well.
Each table contains rows called records and columns called fields.
A record is a collection of facts about a particular person, event, CD, or other item of interest.
A field is a single kind of fact that may apply to each person, event, or other record
The fields in your database have settings that determine the type of data they can store, how the data is displayed, and what you can do with the data.
One important setting for fields is the data type, including number, text, currency (money), and date/time (shown together as one type in Access). The data type limits and describes the kind of information in the field. The data type also determines the actions you can perform on a field and how much memory the data uses. Fields also have properties that control the details of information inside them, including a character length, a default value, and a validation rule that makes sure the data meets certain criteria. The properties make it easier to enter and manage data.
To distinguish one record from another, tables can contain a primary key field.
The primary key is an identifier—such as a part number, a product code, or an employee ID—that's unique to each record.A primary key separates similar information and makes each record unique. It also brings information together. You relate one table to another using a primary key. This is how tables share data, and how you can avoid repeating information in both the tables.
Sunday, February 13, 2011
Tuesday, February 8, 2011
Definitions of Database
Field- Any number of columns regularly used for recording the same information.
Record- A group of related fields, or a single field, treated as a unit and comprising part of a file or data set, for purposes of input, processing, output, or storage by a computer.
File- A collection of related data or program records stored on some input/output or auxiliary storage medium.
Query- A user's request for information, generally as a formal request to a database or search engine.
Database- A comprehensive collection of related data organized for convenient access, generally in a computer
Report- output, especially printed, containing organized information.
DBMS- Data Base Management System: software that mediates access to, additions and deletions of, and changes in data contained in a database, so as to store and access data efficiently and control which data particular programs or individuals are allowed to use.
Data Dictionary- A data structure that stores meta-data, i.e. data about data. The term "data dictionary" has several uses. Most generally it is a set of data descriptions that can be shared by several applications. Usually it means a table in a database that stores the names, field types, length, and other characteristics of the fields in the database tables.
Data Type- A data type (or datatype) In programming, a classification identifying one of various types of data, as floating-point, integer, or Boolean, stating the possible values for that type, the operations that can be done on that type, and the way the values of that type are stored.
My database
Record- A group of related fields, or a single field, treated as a unit and comprising part of a file or data set, for purposes of input, processing, output, or storage by a computer.
File- A collection of related data or program records stored on some input/output or auxiliary storage medium.
Query- A user's request for information, generally as a formal request to a database or search engine.
Database- A comprehensive collection of related data organized for convenient access, generally in a computer
Report- output, especially printed, containing organized information.
DBMS- Data Base Management System: software that mediates access to, additions and deletions of, and changes in data contained in a database, so as to store and access data efficiently and control which data particular programs or individuals are allowed to use.
Data Dictionary- A data structure that stores meta-data, i.e. data about data. The term "data dictionary" has several uses. Most generally it is a set of data descriptions that can be shared by several applications. Usually it means a table in a database that stores the names, field types, length, and other characteristics of the fields in the database tables.
Data Type- A data type (or datatype) In programming, a classification identifying one of various types of data, as floating-point, integer, or Boolean, stating the possible values for that type, the operations that can be done on that type, and the way the values of that type are stored.
My database
Databases commonly used are:
Google
Yahoo
Wolfram Alpha Oracle
Dictionary.com
Thursday, February 3, 2011
Database
What is a database?
A collection of data; information stored, typically in electronic format. It may contain bibliographic, numerical or other data, generally structured so that it can be sought and retrieved automatically.
Examples of databases
relational database- The data in a relational database is stored in various data tables. Each table has a key field which is used to connect it to other tables. Hence all the tables are related to each other through several key fields. These databases are extensively used in various industries and will be the one you are most likely to come across when working in IT.
Examples of relational databases are Oracle, Sybase and Microsoft SQL Server
Operational database- An operational database is usually hugely important to Organisations as they include the customer database, personal database and inventory database ie the details of how much of a product the company has as well as information on the customers who buy them. The data stored in operational databases can be changed and manipulated depending on what the company requires.
A collection of data; information stored, typically in electronic format. It may contain bibliographic, numerical or other data, generally structured so that it can be sought and retrieved automatically.
Examples of databases
relational database- The data in a relational database is stored in various data tables. Each table has a key field which is used to connect it to other tables. Hence all the tables are related to each other through several key fields. These databases are extensively used in various industries and will be the one you are most likely to come across when working in IT.
Examples of relational databases are Oracle, Sybase and Microsoft SQL Server
Operational database- An operational database is usually hugely important to Organisations as they include the customer database, personal database and inventory database ie the details of how much of a product the company has as well as information on the customers who buy them. The data stored in operational databases can be changed and manipulated depending on what the company requires.
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