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There are good reasons why your data should be categorized in to different types. In this video we'll explore some of them.
Types of Data
Here's a slightly larger list of data types than in the video.
- Text Type Examples
- TEXT
- VARCHAR
- Numeric Type Examples
- INT
- INTEGER
- Date Type Examples
- DATETIME
- DATE
- TIMESTAMP
Here's documentation sites for some other databases where you can see the similarities and differences in data types.
Table columns are defined in
the schema to have certain data types.
0:00
A data type describes
the value to be stored.
0:04
There are several data types you'll
come across on a regular basis.
0:08
There are text types,
numeric types and data types.
0:11
Text types are good for storing names or
descriptions of things.
0:15
Numeric types are good for storing prices,
ages, and quantities of things.
0:20
Dates are good for anything time related.
0:26
While this isn't a comprehensive list
of data types, text, numeric, and
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date types are a good starting point.
0:34
The reason we use types will become
more important as we write SQL later on.
0:37
To help you envisage how its
schema enforces types and
0:42
columns, you can think of
the schema as a coin sorter.
0:46
A coin sorter is used to sort
different types of coins into columns.
0:50
The coin sorter ensures that
only the correct coin types go
0:54
into the correct column.
0:58
Like the coin sorter,
0:59
the database schema prescribes what data
should go into each column of the table.
1:00
You may be asking, why even do this?
1:06
Let's look at some examples to see why
it's important to have data types.
1:08
Imagine everything in this
product table was just text.
1:13
The name, price,
stock count, are all text.
1:17
If I wanted to sort by the current stock
count, what result do you think I'd get?
1:21
Well, it'd be sorted like this.
1:26
This is because the stock count is sorted
alphabetically, and not numerically.
1:29
Let's change the price and
the stock count to a numeric type and
1:34
sort by stock count again.
1:38
That looks better.
1:40
Having correct data types in your
database not only helps with sorting but
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it also comes in handy for
1:46
many other applications such as
generating the sum of all sales figures.
1:48
Generating a sum and
1:53
other mathematical operations can only
be done by using with a numeric type.
1:54
Trying to do math with text is impossible.
2:00
In the case of an events table for an
event planner where the new data is added
2:04
all the time, the data is retrieved in
the order it was entered by default.
2:08
If the date of the event
column was just text and
2:14
you attempted to sort it,
it would look like this.
2:16
However if the date of the event
was correctly at date type,
2:20
it would sort like this.
2:24
Understanding that column date types
can affect how data is retrieved
2:27
helps people design the schema for
the database.
2:32
While we're not designing the schema
ourselves in this course,
2:35
understanding data types
will also help us understand
2:38
how we compose the SQL queries
throughout this course.
2:42
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