Databases
Databases is a collected amount of data in an organised manner and now a day in a computer-based form. The term database is used correctly in the applied manner to the data and into their supporting data structure and their do not support the database management system and the term database system implies that the data is managed to some type of quality and it is measured in the terms of accuracy, availability, usability and resilience. Also the database is also used for storing managing and retrieving information. You can use do all of this through the way of tables, it is similar to the spreadsheet like Excel. Even though it isn't much of a spread to make a spreadsheet from a database.
The main features
The main features of a database are the pre-made customisable templates, the calculated fields for powerful database applications, permissions and access, integrated search, mail merge, Import/Export Data Between Databases and Applications, relational database capability, customisable views and printable reports, rich set of field type and complete integration. All of these features are beneficial towards the database system because in the pre-made customisation templates they can access your data on-line quickly by using the customisation-able database templates and every template is always ready to be customised and you can also design it in your specific design and needs. As it goes for the others they all link together in some form because the permissions and access and the integrated search are similar because without the permission the integrated search will become faster then it already is and if it wasn't for the integrated search then the permission and access wouldn't run very fast. There are also other main features that are very important to a database like the:
Entities/ tables - databases will use tables to store the data and it allows you to view all the data that is help within the database, also data can be stored in countless amounts of tables and databases can store a lot of tables.
Attributes/ fields - a field is made up of a single piece of data/information inside a record which is called a 'record'
Records - this is a record of different types of individual pieces of information and it might consist of such items like first/last name, age and city and this type of information is called a field.
All of the above are ways in which the databases can store, receive or send certain data to another piece of the database program system and some of the above like the Attributes/ fields can play to the database strengths because for every piece of information that gets stored into the database it will add itself to the attributes of the system.
Data types
Databases are always stored as data and in order to make this data more efficient also the different types of data are usually can be classed as a certain 'data types'. There are a variety of data types that are necessary of knowing and the main ones include:
Text/ alphanumeric
Number/ numeric
Currency
Date/ time
Boolean
Image
The data types can be useful because the data types can be used to automatically update format data, IE for the currency data type would put the dollar or pound sign in front of whatever the figure is.
Relationships
For the relationship for the database, the data is split up into sensible data groups, for example the customer data, pets and appointment data, then it will be separated into a table in which then each category they are split up into groups and once the tables have been set up the relationship can be created to link all of the system data together. the main benefits of the relationship status of a database is the this data doesn't have to be duplicated but when someone gets an appointment for their animal a completely new record on the appointment table and it will make more relevant for identifying the animal that is chosen/ selected. Also if you were to reduce the amount of data duplication and the amount of data that can be stored and therefore making the database system much smaller. Also reducing the data duplication also reduces the risk of making mistakes because for every mistake that is made you will have to retype every piece of data that was lost and there is also a risk that you could by chance mis-spell any words by mistake.
Electronic v paper
In the electronic section there are many things that the electronic computers can do that the paper-based cannot do, for example in the electronic computer they can store vast amount of data within the hard-drives of the computer and once the hard-drive is full you can easily replace it and not harm the environment while in the paper-based you will have to write down all the necessary information and if you were to make a mistake then you have basically just wasted a whole sheet of paper. Also Electronic has made it much easier to search for all of the necessary because you have the internet to help but for the paper-based you will have to go to the nearest library and search for the books that are needed for the information. Also reports can be created by using databases or queries can be ran through the databases but if you were to create a report on paper it will take too long to create the report and or queries.
Interfaces
The advantages of the interfaces is that it is easy to use and it will make it easier for people who haven't used the interface system before and then they can work out what to do but a disadvantage of the ease of use is that it has a poorly designed menu interface and it may be seriously slow at times to use. Another advantages and disadvantages of the interfaces is that there is no commands to learn or remember so it would be easier to use. While a disadvantage of having no commands is that it could get irritating because there may be too many menu screens for you to work through and who ever is viewing the menu screen will eventually get bored and then leave the page. Also there is step-by-step options to help the user if they cannot remember what to do but the disadvantage of this would be that you cannot too often go to the exact place that you were each time and at the start. Also in order for the database to actually work it will need some items in order to work properly like the
Switchboard so you can change the where you want to place a certain item. Also a switchboard has two meanings: telephone and database. A telephone is when a telephone is linked up to the switchboard in which people can manually move and to connect other people with each other but now-a-days switchboards are all automatic. As for the database; a switchboard is a menu switch within the database management system like Access. When a database has finally been created the creator of that database will create a switchboard for that database which allows simply commands to be said and done but then the user doesn't have top know the full details of the query.
Forms. This is a data entry tool, this form can contain one or more 'fields' because a field is a certain area in which allows you to enter data into that particular data. Also a field can have a 'label' to describe what their purpose is. there are also electronic forms but the most common feature in the 'drop-down' box but in which you can select your choice.
And the reports is a document (electronic vs paper) that presents the easily read and that it is in a professional format and the reports can be created in a database via applications like access.
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Relational Integrity
The relational integrity can use the foreign keys to match the linking primary key and the relational integrity uses the primary and foreign keys to ensure that there are no lost records in the database system, also this can alert you if you try to delete a record. Also the cascade changes can be made to the database if it is necessary.
Primary keys
A primary key is a field in the table which enables you to see all the unique information that is in that table which will include numbers, transactional numbers and so on also they always tend to be at the top of the tables. For example in a school there will be the student/ teacher ID number and they will be most likely at the top of their tables. Also it can only be in one table but it can link to other tables to make it a record.
Foreign keys
A foreign key can be used to link the tables together and therefore a relationship of the tables is created. Also it is the field that is in one table is linked to a primary key in another table. In tables those that are identically named as fields and it is also known as foreign key.
Examples of the different types of relationships are 1-1, 1-many, many-many and many-1 for when you relate "1 to many" this can be used for when you buy films because you as the '1' and buy 'Many' films then it would be in the database. Another example to the 1-1 having a passport for a person but an exception for criminals. An example of a 1-many relationship would be a car and its parts because a car cannot be a car without its parts and a many-many relationship example would be hotel booking.
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Common errors of database
Incorrect data types is when you accidentally enter the necessary data incorrectly then an error message will appear on your screen for example accidentally misspelling a name and getting a ID number wrong but way to correct this will be to re-read before you save also you might need to include the validation rules in so that it can tell you if you have made any mistakes during the creation of the database. Other examples of common errors of the access database is: the file couldn't be found, the file is unknown, two few parameters, key word was not found in any record or cannot update database or object is "read-only" ways that you can overcome these types of errors is for the "cannot update, database or object is read-only" if it cannot update then get an stronger server or convert the document so you will be able to edit the 'read-only' document and you'll might have to contact the space provider to ask them how to sort the problem out. Also the 'too few parameters' the way to sort that from a problem to a solution is that you'll need to check to see if the SQL is correct and to check to see if you haven't misspelled and of the necessary data in the records. As it goes for "file cannot be found" this can solved by check to see if the path to the database is correct and you'll make sure that you'll use the physically pathway on the server and not a virtual pathway.
The other common errors of a database are Accidental Loss of Data and Null Values, these two are the two main common errors of a database. Accidental Loss of Data is when you accidentally delete a column in a table and the ways that you can prevent or at least slow down these errors is to back-up your data on a regular basis and do not let users work directly in a database because if someone were to work directly within the database they could seriously affect the database but if you give them like a data form to fill out then the data can get placed in the database then there would be no damage done to the database. As it goes for Null Values, a Null Values is when a section of a database form isn't filled in properly or isn't filled in at all but ways that these can be prevented is to in validation rules and/or an error message because of someone included validation rules and/or an error message then they would be restricted of leaving the page until they have completed the form correctly or if you incorrectly typed in a name wrong then a message would appear saying "incorrect name" or "too young".
Validation is when you can restrict certain access if someone has unsuccessfully fulfilled a box in the database then the ways in which these rule can be backed-up is to create the validation rules during the creation of the database because if you create a validation rule during the creation then at the end of the creation then people use it then and get it wrong then the validation rule come into place basically blocking them from continuing. Examples of the validation rules are <>0 this is the nonzero value and there is also >=0 this means that the number must be zero or greater or you must enter a positive number into the table.
Incorrect Data Types and Renaming Incorrectly are similar in the problem solver but in the Incorrect data types for when someone enters data into a database incorrectly an error message will appear saying that you have mis-spelt a name wrong or typed in a number wrong then the message will appear and for the renaming incorrectly the same will appear because of the validation rules that are in place to stop deletion of the database
