Data is all around us, but few understand how to conceptualize it. There are data sets, data tables, data attributes, data fields, databases, data lakes, data marts, data objects, and a whole lot more.
You shouldn’t let these terms overwhelm you. Data itself is quite simple. But because it’s so simple, analyzing it’s different faces is hard. That’s why data pioneers invented specific terminology. It’s an easy way to talk about elements that are hard to distinguish by description alone.
The term they developed for the smallest and most fundamental element is “data item.” A data item represents the piece of information you find in one cell of a data table, representing one trait of one observation.
With that said, over time the term has come to carry different meanings across platforms and coding languages.
The purpose of this article is to define what data items are, provide examples, and discuss their use in programming languages C, Python, and HTML.
A data item represents a single trait of an object or concept, in a specific place, at a specific point in time. Data items are subcomponents of data objects and represent the atomic state of an object or concept with the given contraints.
While they usually appear as number is a cell of a data table, data items do not need to be recorded to exist. Instead, every object and concept contains a near-infinite number of data items at each point in time. Data analysts aim to capture the relevant data items, explore them, and gain insights.
While this may seem hard to understand in theory, it’s quite simple in practice. Every time a data analyst records data in a cell, s/he records a data item. What’s more, you yourself contain a near-infinite number of data items just waiting to be recorded.
Your brunet hair is a data item. The length of your toenails in a data item. Your pulse is a data item. Your address is a data item. Which data items are collected is simply a question of what information the data analyst wants, and the measurement tools available.
Don’t forget, you can the free 67 data skills and concepts checklist to make sure you’ve got your bases covered (including data items).
Types of Data Items
So, data items are just data in a cell,l. But are their different kinds, or types of data items? The short answer is yes. Data analysts categorize data items based on their features. Numerical data, for example, are different from textual data. Let’s look at these _____ types of data items:
- Integer – any number that doesn’t have a decimal point
- Date – a date of a given year and month
- Time – the time of day
- Text – often referred to as “string,” means simply any combination of letters instead of numbers or other symbols
- Boolean – TRUE or FALSE data, often migrated to YES or NO text, or 1 and 0 numbers. It is, in simple terms, binarydata.
The above examples are simple, big-picture data item types, but they’re far from comprehensive. In fact, we can dig deeper with the following list:
- Numeric Data Item Types
- Integer – any number that is not a decimal. Examples include -11, 34, 0, 100.
- Tinyint – an integer, but only numbers from 0 to 255
- Bigint – an integer bigger than 1 trillion
- Float – numbers too big to write out, and the scientific method is needed
- Real – any fixed point on a line
- Date and Time Data Item Types
- Date – the date sorted in different forms, including “mm/dd/yyyy” (US), “dd/mm/yyyy” (Europe), “mmmm dd, yyyy”, and “mm-dd-yy” among many more.
- Time – the time of day, broken down as far as milliseconds
- Date time – the date and time value of an event
- Timestamp – stores number of seconds passes since 1970-01-01 00:00:00’ UTC
- Year – stores years ranging from 1901 to 2155 in two-digit or four-digit ranges
- Character and String Data Item Types
- Char – fixed length of characters, with a maximum of 8,000
- Varchar – max of 8,000 characters like char, but each entry can differ in length (variable)
- Text – similar to varchar, but the maximum is 2GB instead of a specific length
- Unicode Character and String Item Types – unicode is a way of structuring data in the form of U+0000, where the 0’s can be any type
- nchar – fixed length with maximum length of 8,000 characters
- nvarchar – variable length with maximum of 8,000 characters
- ntext – variable length storage, only now the maximum is 1GB rather than a specific length
- Binary Data Item Types – a combination of 0s and 1s
- binary – fixed length with maximum of 8,000 bytes
- varbinary – variable length storage with maximum bytes, topped at 8,000
- Miscellaneous Data Item Types
- clob – also known as Character Large Object, is a type of sub-character that carries Unicode texts up to 2GB
- blob – carries big binary objects
- xml – a specific data type that stores XML data. XML stands for extensible markups language, and is common in data bases
Difference between Data Attribute and Data Item
While we won’t show comparisons between data items and all data terminology, it’s important to see the difference between data items and data attributes.
A data item is the distinct information that describes one observation under an attribute, whereas a data attribute itself distinguishes the group data items can be used to describe the observation.
That sounds complicated. In short, if you’re looking at data about monkeys, and one of the things you want to know is how tall they are, “height” is the attribute. Then, “3ft” would be a data item. This table above illustrates this.
In other words, data attributes define the possible data items that can be used to describe an observation.
Data Item vs Data Field
Another important data term is data field. For most intents and purposes, data field is a synonym for data attribute. The only nuance is that we use the word “field” in the context of a data table, whereas we use “attribute” to describe the possible data items in tables, objects, data models, and any other data context for that matter.
For example, imagine again our monkey table:
In the case, “height” and “weight” would be data fields. At the same time, we can call them data attributes. Whatever we call them, the data items are “3ft,” “4ft,” “3.5ft,” “20lbs,” “15lbs,” and “50lbs.”
Data Items in C
We’ve looked at data items from a database perspective, but the term is also common in programming languages, where it carries a slightly different function.
Data items in C represent the same atomic-level information as they do in data tables. The difference lies in how programmers can treat them. C allows programmers to group together a set of data items into a data structure, and treat that data structure as a data type. That’s right–while data items fall into categories of data types, C is capable of bundling a group of them together and inventing its own data type.
If you’re not a programmer, this may seem abstract. Truth be told, as a data or financial analyst you will rarely use C, so you don’t need to understand the theory. The key here is that you may hear programmers refer to data items in the context of data structures, rather than databases.
data.items() in Python
In python, the process is quite similar. The core meaning of data items remains the same, but programmers can use the data.items() function to create their own data structure and assign it a data type.
This function in python differs from C insofar as the syntax and relationships to other data objects vary. C is a procedural computer programming language, whereas python is a general-purpose, high-level language.
As opposed to C and python, data items in HTML are not the same as data items in databases. This is mainly due to the fact that HTML is not a real programming language, but a mockup language.
It does not run commands on server-side databases or create and store data. It simply shows how an internet page should be built. In fact, languages such as Php, where are programming languages, usually call on HTML frames.