# What exactly is A dataset? is a database contain more than 2 tables counted as 1 or 2 datasets?

A data set (or dataset) is a collection of data. Most commonly a data set corresponds to the contents of a single database table, or a single statistical data matrix, where every column of the table represents a particular variable, and each row corresponds to a given member of the data set in question.

It seems that the iris data set could be counted as 1 dataset.

Is a database that contains more than 2 tables counted as 1 or 2 datasets?

• Relational database tables are not referred to as datasets. They are just tables. You can create one or more datasets from those tables, potentially combining data from different tables. – AlexK May 20 '19 at 7:45

A dataset might refer to any collection of information about a specific topic. Namely, a file, an excel file, a .txt file, etc.

Usually, we use datasets that are saved in a table format (like .csv files) a dataset in this form is exactly like a table having columns (fields) for the name of its features and rows that are the records (samples) and an index for each row. A problem might be solved using multiple datasets (tables) but each dataset is referred to a single table (data frame)

Whatever the format is, for utilizing, we turn the dataset to a table (dataframe)

This is almost a philosophical question. IMO you could view a library or a collection of photos as "a set of data". So what is a set (https://en.wikipedia.org/wiki/Set_(mathematics))? A set is a collection of elements (often non-redundant and with a certain inherent logic). The iris data is a good example.

I see a database more like a set of sets. A database is a tool (or institution if you like) to store data in a structured way. So in a database you can have any kind of data, but a database provides you with information where to find certain data(sets).

If you have two sets A={1,2}, B={f,g}, you could view A, B as datasets. If you form a set of sets L={A,B}={{1,2},{f,g}} you could see this as a database. However, a database will usually allow you to rearrange data, e.g. you could form a new (data)set from L, such as C={2,f,g}.

From a practical perspective: usually you work with structured machine readable data (tables or dataframes) stored in files (csv, xls etc.) which are referred to as datasets. However, there are applications in which data are "streamed" from a database to work with it. But even streamed data from a database is a (sub)set of the database.