What is a DBMS?
Packages based around the need to hold a collection of centralised and structured data for further manipulation in various ways
What does a DBMS do?
– Allow the database to be defined
– Allow users to query the database
– Allow the user to modify the structure of the database
– Provides adequate security for the data held
What can DBMS do with data?
Allows data to be appended, deleted and edited
Advantages in using a DBMS
– It makes people think about the data being stored, and stores it in a logical and structured way
– Data can be kept separate to the applicants using it
– Avoids data redundancy
– Data integrity is maintained
– Increased security
Disadvantages in using a DBMS
– Learning how to use a DBMS can be difficult
– Costs for the development of a DBMS can be very high
– The whole data is stored in a central location which means it is more vulnerable
The process of keeping information uniform as it moves across a network and between various applications on a computer. There are typically three types of data consistency: point in time consistency, transaction consistency, and application consistency.
Data redundancy in a database means that the same data is present in more than one table. Or in the case of a flat file database, there are records with partly duplicated data
Data integrity is a term used to refer to the accuracy and reliability of data. Data must be complete, with no variations or compromises from the original, to be considered reliable and accurate
Data independence is a form of database management that keeps data separated from all programs that make use of it
Relational database organisation
Data normalization is the process of reducing data to its canonical form. For instance, Database normalization is the process of organizing the fields and tables of a relational database to minimize redundancy and dependency
What is the difference between a primary key and a foreign key
PK: A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records
FK: A foreign key is a column or group of columns in a relational database table that provides a link between data in two tables. It acts as a cross-reference between tables because it references the primary key of another table, thereby establishing a link between them.