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.

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

	Duration	Average_Pulse	Max_Pulse	Calorie_Burnage	Hours_Work	Hours_Sleep
	Column 1	Column 2	Column 3	Column 4	......	......
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
	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

A row is a horizontal representation of data.

A column is a vertical representation of data.

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 9 columns, meaning that there are 9 variables.

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.

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

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

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

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

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

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