When working with databases, the data kept in a single table can always be in relation to data kept in a different table. In order for a database to function as it should, the relationship needs to be adequately designated.
To do this, you need to use primary keys, and also foreign keys.
These keys are in practice as a way in which to link relative data inside a database. It makes sure that the data always stays consistent, and there is never any redundant data in the database.
So, if you were to delete a table, or even just a row that another table relies on, the redundant data will be removed overall.
This process ensures the prevention of integrity issues inside a database which could otherwise cause issues within an application that makes usage of particular data.
This is the basis of primary keys. However, we want to deeper understand the purpose of primary keys and why they are used.
So, today we will talk about primary keys, what they mean, explain the use of them, and all related information. After today, you can leave this page knowing you know everything there is to know about primary keys and their purpose.
What Is A Primary Key? What Does It Mean?
Let’s start by briefly explaining what primary keys mean.
A primary key is basically a special relational database table column, or in some cases a combination of columns, which is designed to individually recognize every table record there is.
A primary key will be functional as a specific identifier to resolve data in a table. Hence, a table is unable to have any more than a single primary key.
The main functions and features of a primary key are that it has to contain a specific value for every row of information there is. A primary key cannot contain any null values, and each row has to have a value for a primary key as well.
A primary key may also utilize one or perhaps more fields that are present in a particular data model, otherwise a specific additional field could also be crafted to be a primary key.
This is the basics of what this phrase means.
Before we move on, there is something more we want to say about primary keys. They are important for many reasons, however their concept is absolutely imperative to any functional relational database out there.
Without any primary key and their closely related cousins – the foreign concepts, related databases key would simply not function. It wouldn’t work. This is a significant feature that keeps databases running and prevents the relational databases from breaking down.
A single table could contain hundreds, thousands, or more records, and so a primary key is significant in order to be certain that any table record could at any time be quickly and uniquely identified by the viewer.
Any keys that might come from a world observable, and world attributes are known as natural primary keys, in opposition to their alternative cousins surrogate primary keys which are otherwise indiscriminately assigned to every record.
Without knowing it, everyone encounters natural primary keys in normal day-to-day life, we all do it, we just do not know it. ID numbers for example, your social security no., your driver’s license, your addresses, and so on are all examples of this.
What Is It Used For?
Now, we want to talk about what these keys are specifically used for in more detail. Although, we think you probably already know.
Primary keys are essential to a table, if it is to be eligibly defined as being relational. A primary key is compounded of one or many columns in which the data uniquely classifies each row in said table.
So, if there was data in a particular row that was to contain phone numbers, then the keys may be used to identify countries, phone providers or so on.
For any data to qualify as being a primary key, the data in each column must be individual, this means it is not just the name of the column itself. However, that being said, should a column be back or null it has no value.
Primary keys have many uses, but one of the foremost ones is to craft users tables. ID columns are often the primary keys in this case, as it is unique as it is required to be. In this case, you may set this to ‘auto-increment’, however the most important part to remember is the primary key.
Why Do You Need One?
Why do you need a primary key? Well, we think you know why now. The main reason is that you have to have one for a table to be relational with other tables.
Even should a column be designated as a foreign key, if it has duplicated data in many of its rows, then it does still rely on unique details found in the primary key.
If there was no unique information in a column, then there would be no use for a foreign key, the two are intertwined.
You may be mapping out a singular row in the foreign key to what could be two possible rows found in the primary key.
Basically, to break it down, a primary key makes certain that any data inserted into a table that has a foreign key can only ever be data that will exist in a unique sense within the primary key’s column.
Also, if there happens to be a deletion or an update, the action is performed to ensure that the data retains integrity and prevents any redundancy of data within your database.
To wrap up, we ask, ‘what is the purpose of a primary key?’ and the answer is actually super simple.
Primary keys keep data regulated across your database. If something changes in your database, if a column is updated, the primary key ensures this information is carried across relevant databases.
Obviously, this keeps things simple and stops you from having to update things across the board from one minor change, but it also keeps information and data secure and prevents any redundancies inside your database.