In this module, we discussed
- rows and
as the elements that make up a relational database system.
You also created a table, figured out how to add an index, inserted information into the table, and queried the table to see the information you inserted. It is important to understand firmly what each item refers to. The exact syntax for creating the tables can be referenced by the version of SQL that you are implementing. You need to make sure you understand the specific process and the end result that you are trying to achieve.
You will need to fully understand the differences between tables, databases, rows and columns to effectively build SQL statements. These are key elements not only in the course project and examples, but also in the everyday use of SQL.
To implement data modeling with a database, you need to understand simple concepts,
such as the difference between a database model and a database.
A database model is a blueprint for how data is stored in a database and is similar to an architectural approach for how data is stored,
a diagram commonly known as an entity relationship diagram
A database is the implementation or creation of a physical database on a computer. A database model is used to create a database.
As a natural progression of improvements in database modeling, the relational database model has evolved into what
it is today. Each step in the evolutionary development of database modeling has solved one or more problems.
The final step of database modeling evolution is how applications affect a database model design.
An application is a computer program with an user interface, where end-users use browsers or tablets to access data in a database.
Different types of applications use a database in different ways and this can affect how a database model should be designed.
Before you set off to figure out a design strategy, you must have a general idea of the kind of applications your database will serve.
Different types of database models construct different types of applications, and one must understand
where different types of database models apply. It is essential to understand that a well-organized design process is paramount to success.
A project plan to drive the design process is equally as important as the design itself.
There is no point in designing or building an application and database, unless the target goal is established first.
- a table is an organized set of data elements using a model of vertical columns (which are identified by their name) and horizontal rows.
- The cell of a table is the unit where a row and column intersect.
- A table has a specified number of columns, but can have any number of rows.
- Each row is identified by the values appearing in a particular column subset which has been identified as a unique key index.
- Table is another term for relation; although there is the difference in that a 1) table is usually a multiset of rows and 2) a relation is a set that does not allow duplicate elements.
Besides the actual data rows, tables generally have metadata associated with them, such as constraints on the table or values within particular columns. The data in a table does not have to be physically stored in the database. Views are also relational tables and their data is calculated at query time