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Indentation rules
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@ -5,7 +5,7 @@
These are guidelines to help you write SQL queries that will be easier to read.
Remember that even if you hate a given style at first, generally speaking it is
far more important that we have _any_ agreed upon style than that we all like it,
far more important that we have _any_ agreed upon style than that we all like it,
and furthermore the odds are that you will eventually learn to like it once you
start to follow it.
@ -153,6 +153,37 @@ WHERE p.release_date > '2014-09-30';
To make the code easier to read it is important that the correct amount of
spacing is used. Do not crowd code or remove natural language spaces.
### Indentation
To ensure that SQL is readable it is important that standards of indentation
are followed.
**ONLY** the fundamental keywords - `SELECT`, `FROM`, `WHERE`, `GROUP BY`, `HAVING`, `LIMIT`,
and `ORDER BY`should be fully left justified.
For single `SELECT`s, you can use the single line form:
```sql
SELECT first_name
FROM rappers
```
If you are `SELECT`ing more than one column, place all selects on their own line indented 2
spaces in a block after the `SELECT` keyword.
```sql
SELECT
first_name,
last_name,
is_still_tippin_on_four_fours,
is_still_wrapped_in_four_vogues
FROM rappers
WHERE first_name = 'Mike'
AND last_name = 'Jones'
```
This allows the reader to quickly scan for the important building blocks of the query.
#### Spaces
Although not exhaustive always include spaces:
@ -163,7 +194,10 @@ Although not exhaustive always include spaces:
comma or semicolon.
```sql
SELECT a.title, a.release_date, a.recording_date
SELECT
a.title,
a.release_date,
a.recording_date
FROM albums AS a
WHERE a.title = 'Charcoal Lane'
OR a.title = 'The New Danger';
@ -198,36 +232,16 @@ WHERE title = 'The New Danger';
```
```sql
SELECT a.title,
a.release_date,
a.recording_date,
a.production_date
SELECT
a.title,
a.release_date,
a.recording_date,
a.production_date
FROM albums AS a
WHERE a.title = 'Charcoal Lane'
OR a.title = 'The New Danger';
```
### Indentation
To ensure that SQL is readable it is important that standards of indentation
are followed.
**ONLY** the fundamental keywords - `SELECT`, `FROM`, `WHERE`, `GROUP BY`, `HAVING`, `LIMIT`,
and `ORDER BY`should be fully left justified. Other clauses should be indented to the end of
that keyword.
```sql
SELECT first_name,
last_name,
is_still_tippin_on_four_fours,
is_still_wrapped_in_four_vogues
FROM rappers
WHERE first_name = 'Mike'
AND last_name = 'Jones'
```
This allows the reader to quickly scan for the important building blocks of the query.
#### Joins
Joins should be indented 2 spaces right from the `FROM` keyword
@ -277,27 +291,30 @@ FROM my_tmp_table
#### Sub-queries
In PostgreSQL you should probably be doing subqueries with `WITH` clauses.
In PostgreSQL you should probably be writing subqueries with `WITH` clauses and mostly avoiding the
use of inline subqueries.
Sub-queries should be left aligned 2 spaces to the right of the opening parentheses and then
laid out using the same style as a `WITH` statement w/r/t parentheses.
In MySQL or other query engines that do not support `WITH`, sub-queries should be left aligned 2
spaces to the right of the opening parentheses and then laid out using the same style as a `WITH`
statement w/r/t parentheses.
```sql
SELECT r.last_name,
(
SELECT MAX(YEAR(championship_date))
FROM champions AS c
WHERE c.last_name = r.last_name
AND c.confirmed = 'Y'
) AS last_championship_year
SELECT
r.last_name,
(
SELECT MAX(YEAR(championship_date))
FROM champions AS c
WHERE c.last_name = r.last_name
AND c.confirmed = 'Y'
) AS last_championship_year
FROM riders AS r
WHERE r.last_name IN
(
SELECT c.last_name
FROM champions AS c
WHERE YEAR(championship_date) > '2008'
AND c.confirmed = 'Y'
)
(
SELECT c.last_name
FROM champions AS c
WHERE YEAR(championship_date) > '2008'
AND c.confirmed = 'Y'
)
```
#### Case statements (PostreSQL)