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You're not restricted to displaying the column names from the table at the top of your results. You can specify your own names for result sets.
SQL Used
SELECT <column name> AS <alias> FROM <table name>;
SELECT <column name> <alias> FROM <table name>;
Examples:
SELECT username AS Username, first_name AS "First Name" FROM users;
SELECT title AS Title, year AS "Year Released" FROM movies;
SELECT name AS Name, description AS Description, price AS "Current Price" FROM products;
SELECT name Name, description Description, price "Current Price" FROM products;
See all of the SQL used in SQL Basics in the SQL Basics Cheat Sheet.
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Let's select everything
from our books table again.
0:00
We have an ID, which is a unique
identifier for the database entry.
0:03
This is a common practice and guarantees
that every row is not a duplicate of
0:07
another, and can be isolated
from all other rows if needed.
0:12
We have the title, author,
genre, and first_published.
0:16
Remember, querying a table's
contents allows us to present
0:22
the results of a database
in many different ways.
0:26
The results are designed for
humans to read.
0:29
But sometimes the column
names aren't that friendly.
0:32
Let's say I was running a query for
the library administrator.
0:35
They want a report of all the books in
the database along with the year that they
0:38
were first published.
0:42
The column headers are all in lower case.
0:47
This may be distracting
to the report reader.
0:50
We can change the title of any column,
by using the keyword AS.
0:53
After the AS, you can write what you
want to alias the column name to.
0:58
Let's use Title with an uppercase T.
1:02
When we run the query now, we get
the results back with a capital T
1:06
in the title column.
1:10
How about the first_published column?
1:12
We can use the AS keyword again but
with the words First Published.
1:15
If you try and execute this query,
you'll get an error.
1:23
Error: near "Published": syntax error.
1:26
The key for
us here is that it's a syntax error.
1:29
Remember the syntax is the grammar or
1:33
the rules surrounding the way
we write programming code.
1:35
The computer doesn't
understand the word Published.
1:39
It's expecting a FROM or a comma,
followed by another column name.
1:42
We can't use multiple words like
this when writing SQL queries.
1:47
So what do we do for something such as
our first_published alias, in our reports?
1:52
There is a way we can
use some punctuation,
1:57
which is part of the SQL syntax,
to solve this problem.
2:00
We can define column names with spaces
by wrapping them in quotes like this.
2:03
The opening quote is just
before the first letter, and
2:10
the closing quote after the last letter.
2:13
But here's another got ya.
2:17
Writing SQL in different
databases like Microsoft SQL, or
2:19
PostgreSQL my require you to use different
punctuation for writing aliases.
2:22
Some require single quotes,
others even require square brackets.
2:28
The SQL we're using in SQL Playground can
use double quotes, but just be mindful.
2:32
SQL in different settings may have
these slight variations in syntax.
2:38
Most database documentations have help
to guide you around these difficulties.
2:43
When we execute this query now,
we see Title and
2:47
First Published with a space
as the column titles.
2:51
There is a short hand for this syntax,
where you remove the AS keyword.
2:55
You can try it too.
3:02
See?
3:05
It's the same results.
3:06
I avoid this syntax because
it's not very clear.
3:08
I just wanted to bring you up so
3:11
you weren't confused if
you saw it somewhere else.
3:12
To recap, to alias a column name
to something of your choosing,
3:15
type SELECT <column name> the keyword AS,
followed by the new name.
3:19
So, if I were to bring back all patron
names in a more user-friendly format,
3:27
I could do something like this.
3:32
With quotes around the first name and
last name.
3:34
These characters surrounded by
quote marks are called strings,
3:42
meaning strings of characters,
3:46
letters, numbers,
special characters and spaces.
3:48
One final note about the AS keyword.
3:52
When you bring back data with
a new label using the AS keyword
3:55
it does not change the name of
the column in the actual database.
3:59
For example, when we aliased our
first_published column
4:03
as First Published in our report.
4:07
The column name is always first_published.
4:10
Only in our report do we see the column
represented as First Published.
4:14
This is why we call it an alias.
4:18
As an aside, the AS keyword can
be used to alias table names for
4:22
more complex queries working
with multiple tables.
4:27
We'll be covering that in another course.
4:30
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