1. The document discusses modern features of SQL such as window functions, common table expressions, grouping sets, rollup and cube. 2. It provides examples and explanations of these features and how they can be used to analyze and query data in flexible ways. 3. Compatibility of these features across major database systems such as PostgreSQL, SQL Server, and Oracle is also discussed.

1. Modern SQL
Writing SQL query in 21th century
Cédric Krier
B2CK
http://www.b2ck.com/

2. 2
Cédric Krier @ B2CK
●
Tryton (ERP)
●
python-sql

3. 3
Structured Query Language
●
Domain Specific Language
– Data Query Language (SELECT)
– Data Definition Language (CREATE TABLE)
– Data Control Language (GRANT)
– Data Manipulation Language
(INSERT / UPDATE / DELETE)
●
Relational Database Management System

4. 4
Standard
●
SQL-86 SQL-89 SQL-92
●
SQL:1999 (SQL3)
– Common Table Expression
– GROUPING SETS, ROLLUP and CUBE
●
SQL:2003
– Window Function
– Filter
●
SQL:2006 (XML) SQL:2008 SQL:2011 (Temporal)
SQL:2016 (JSON, LISTAGG)

5. 5
Interoperability
●
PostgreSQL
●
Mimer SQL

6. 6
Data Query Language
SELECT <expression>, …
FROM <table>, …
WHERE <condition>, …
GROUP BY <grouping>, …
HAVING <expression>, …
ORDER BY <expression> ASC|DESC, …

7. 7
GROUPING SETS, ROLLUP and CUBE
GROUP BY GROUPING SETS
((<expression>, …), (…))

8. 8
GROUPING SETS, ROLLUP and CUBE
Example

9. 9
GROUPING SETS, ROLLUP and CUBE
GROUP BY ROLLUP (<e1>, <e2>, <e3>, …)
=
GROUP BY GROUPING SETS (
(<e1>, <e2>, <e3>, …),
(<e1>, <e2>),
(<e1>),
())

10. 10
GROUPING SETS, ROLLUP and CUBE
Example

11. 11
GROUPING SETS, ROLLUP and CUBE
GROUP BY CUBE (<e1>, <e2>, …)
=
GROUP BY GROUPING SETS (
(<e1>, <e2>),
(<e1>),
(<e2>, <e1>),
(<e2>)
(),
)

12. 12
GROUPING SETS, ROLLUP and CUBE
Example

13. 13
GROUPING SETS, ROLLUP and CUBE:
compatibility
●
DB2 ✔
●
MySQL ✘ (WITH ROLLUP)
●
Oracle ✔
●
PostgreSQL ✔
●
SQL Server ✔
●
SQLite ✘

14. 14
FILTER
SUM(<expression>) FILTER ( WHERE <condition> )

15. 15
FILTER
Example

16. 16
Filter: compatibility
●
DB2 ✘
●
MySQL ✘
●
Oracle ✔ (using WITHIN GROUP)
●
PostgreSQL ✔
●
SQL Server ✘
●
SQLite ✘

17. 17
Filter: Alternative
SUM(CASE WHEN <condition>
THEN <expression> END)
⚠ NULL: OK for most aggregate

18. 18
Filter: Alternative COUNT(*)
COUNT(CASE WHEN <condition> THEN 1 END)

19. 19
Window Function: PARTITION BY
SUM(<expression>)
OVER ( PARTITION BY <expression> )
PARTITION divides rows in groups with the same
value

20. 20
Window Function: PARTITION BY
Example

21. 21
Window Function: ORDER BY
RANK() OVER ( ORDER BY <expression> )
rows from the start up through the current row

22. 22
Window Function: ORDER BY
Example

23. 23
Window Function:
PARTITION BY ORDER BY
Example

24. 24
Window Function: compatibility
●
DB2 ✔
●
MySQL ✔
●
Oracle ✔
●
PostgreSQL ✔
●
SQL Server ✔
●
SQLite ✘

25. 25
Window Function: naming
SELECT
SUM(<expression>) OVER <name>,
AVG(<expression) OVER <name>
FROM <table>
WINDOW <name> AS (
PARTITION BY <expression>
ORDER BY <expression> )

26. 26
Window Function: BETWEEN
SUM(<expression>)
OVER ( <RANGE|ROWS>
BETWEEN <start> AND <end> )

27. 27
Window Function: BETWEEN
●
UNBOUNDED PRECEDING
●
<value> PRECEDING
●
CURRENT ROW
●
<value> FOLLOWING
●
UNBOUNDED FOLLOWING

28. 28
Window Function: BETWEEN ROW
CURRENT ROW
UNBOUNDED PRECEDING UNBOUNDED FOLLOWING
3 PRECEDING 2 FOLLOWING
1 PRECEDING 1 FOLLOWING
1 2 3 4 5 6 7 8 9

29. 29
Window Function: BETWEEN RANGE
CURRENT ROW
UNBOUNDED PRECEDING
UNBOUNDED FOLLOWING
1 2 3 4 5 6 7 8 9
10 15 20 25 25 25 25 30 40

30. 30
Window Function: BETWEEN
Default:
RANGE BETWEEN UNBOUNDED PRECEDING
AND CURRENT ROW

31. 31
Window Function: RANGE | ROWS
●
RANGE:
– CURRENT ROW:
●
<start>: first row of peer rows (from ORDER BY)
●
<end>: last row of peer rows (from ORDER BY)
– No <value> PRECEDING | FOLLOWING
●
ROWS:
– CURRENT ROW:
●
Always current row

32. 32
Window Function: BETWEEN
Example

33. 33
Common Table Expression
WITH <name> (<column>,…) AS
(SELECT …)
SELECT …

34. 34
Common Table Expression: multiple
WITH name1 AS(
SELECT …),
WITH name2 AS (
SELECT …
FROM name1)
SELECT …

35. 35
Common Table Expression: compatibility
●
DB2 ✔ (no subquery)
●
MySQL ✔ (> MySQL 8.0 & MariaDB 10.2)
●
Oracle ✔
●
PostgreSQL ✔
●
SQL Server ✔ (no subquery, insert)
●
SQLite ✔

36. 36
CTE Recursive
WITH RECURSIVE <name> (<column>, …) AS (
SELECT …
UNION ALL
SELECT … FROM <name> …
)
SELECT …

37. 37
CTE Recursive
Example

38. 38
CTE Recursive: compatibility
●
DB2 ✔
●
MySQL ✔ (> MySQL 8.0 & MariaDB 10.2)
●
Oracle ✔
●
PostgreSQL ✔
●
SQL Server ✔
●
SQLite ✔

39. 39
Questions?

40. 40
Links
●
https://www.postgresql.org/docs/
●
https://modern-sql.com/