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Data Science - Database Table


Database Table

A database table is a table with structured data.

The following table shows a database table with health data extracted from a sports watch:

Duration Average_Pulse Max_Pulse Calorie_Burnage Hours_Work Hours_Sleep
30 80 120 240 10 7
30 85 120 250 10 7
45 90 130 260 8 7
45 95 130 270 8 7
45 100 140 280 0 7
60 105 140 290 7 8
60 110 145 300 7 8
60 115 145 310 8 8
75 120 150 320 0 8
75 125 150 330 8 8

This dataset contains information of a typical training session such as duration, average pulse, calorie burnage etc.


Database Table Structure

A database table consists of column(s) and row(s):

Column 1 Column 2 Column 3 Column 4 Column 5 Column 6
Duration Average_Pulse Max_Pulse Calorie_Burnage Hours_Work Hours_Sleep
Row 1 30 80 120 240 10 7
Row 2 30 85 120 250 10 7
Row 3 45 90 130 260 8 7
Row 4 45 95 130 270 8 7
Row 5 45 100 140 280 0 7
Row 6 60 105 140 290 7 8
Row 7 60 110 145 300 7 8
Row 8 60 115 145 310 8 8
Row 9 75 120 150 320 0 8
Row 10 75 125 150 330 8 8

A row is a horizontal representation of data.

A column is a vertical representation of data.


Variables

A variable is defined as something that can be measured or counted.

Examples can be characters, numbers or time.

In the example under, we can observe that each column represents a variable.

Duration Average_Pulse Max_Pulse Calorie_Burnage Hours_Work Hours_Sleep
30 80 120 240 10 7
30 85 120 250 10 7
45 90 130 260 8 7
45 95 130 270 8 7
45 100 140 280 0 7
60 105 140 290 7 8
60 110 145 300 7 8
60 115 145 310 8 8
75 120 150 320 0 8
75 125 150 330 8 8

There are 6 columns, meaning that there are 6 variables (Duration, Average_Pulse, Max_Pulse, Calorie_Burnage, Hours_Work, Hours_Sleep).

There are 11 rows, meaning that each variable has 10 observations.

But if there are 11 rows, how come there are only 10 observations?

It is because the first row is the label, meaning that it is the name of the variable.