http://fr.slideshare.net/MarkusWinand/modern-sql SQL has gone out of fashion lately—partly due to the NoSQL movement, but mostly because SQL is often still used like 20 years ago. As a matter of fact, the SQL standard continued to evolve during the past decades resulting in the current release of 2011. In this session, we will go through the most important additions since the widely known SQL-92, explain how they work and how PostgreSQL supports and extends them. We will cover common table expressions and window functions in detail and have a very short look at the temporal features of SQL:2011 and the related features of PostgreSQL.

1. Still using
Windows 3.1?
So why stick to
SQL-92?
Modern SQL in PostgreSQL
@MarkusWinand

2. SQL:1999

3. !"#$%"!

4. Inline views can't refer to outside the view:
!"#"$%&'
&&()*+&,-
&&.*/0&1!"#"$%&'
&&&&&&&&&&()*+&,2
&&&&&&&&&34")"&,256&7&,-56
&&&&&&&8&9:;9:<=>9<?
&&&&*0&19:;9:<=>9<?56&7&,-568
LATERAL Before SQL:1999
Invalid

5. Inline views can't refer to outside the view:
!"#"$%&'
&&()*+&,-
&&.*/0&1!"#"$%&'
&&&&&&&&&&()*+&,2
&&&&&&&&&34")"&,256&7&,-56
&&&&&&&8&9:;9:<=>9<?
&&&&*0&19:;9:<=>9<?56&7&,-568
LATERAL Before SQL:1999
Belongs
there

6. SQL:99 #@%")@# views can:
!"#"$%&'
&&()*+&,-
&&.*/0&!"#$%"!&1!"#"$%&'
&&&&&&&&&&&&&&&&&&()*+&,2
&&&&&&&&&&&&&&&&&34")"&,256&7&,-56
&&&&&&&&&&&&&&&8&9:;9:<=>9<?
&&&&*0&1,AB<8
LATERAL Since SQL:1999
Valid due to
LATERAL
keyword
Useless, but
still required
except
for CROSS join

7. But WHY?

8. Apply #/+/% per row from previous table:
!"#"$%&,CD=DACEBF,G5'
&&()*+&FH,<ICA9<G&F
&&.*/0&#@%")@#&1!"#"$%&'
&&&&&&&&&&&&&&&&&&()*+&DACEBF,G&D
&&&&&&&&&&&&&&&&&34")"&D5FH,&7&F5FH,
&&&&&&&&&&&&&&&&&'%($%&)*&+,-./0&($12
&&&&&&&&&&&&&&&&&!343#&5
&&&&&&&&&&&&&&&8&,CD=DACEBF,G
LATERAL and Top-N per Group

9. Get the 10 most recent news for subscribed topics:
!"#"$%&:5'
&&()*+&:<?G&:
&&.*/0&GBJGFA9D,9C:G&G
&&&&*0&1:5,CD9F&7&G5,CD9F8
&34")"&G5BG<A&7&K
&*)L")&MN&:5FA<H,<E&L"!$
&#/+/%&-O
LATERAL and Multi-Source Top-N

10. LATERAL and Multi-Source Top-N
Sort/Reduce
Join
everything
!"#"$%&$"#'()*+ ,-,%./01(2-3
45%6/.$%&$"#'()*+ ,-,%./01(2-3
%%%6/.$%7'$8/9:%$/;4<%8'=;1/.$%7'#:%*->?
%%%45%@=18%A/"B%&$"#'()** C--%./01(D-E -)D3
%%%%%%45%6'F%6G=B%/B%1HI1G.";$"/B1%1
%%%%%%%%%&$"#'(*+D%./01(C-3
%%%%%%45%@=18%&$"#'(2-J DC+%./01(2-K,3
%%%%%%%%%45%6'F%6G=B%/B%B'01%B
%%%%%%%%%%%%&$"#'(D2 )2C%./01(2-K,3
LM=BB"BN%$"#':%-O)DJ%#1
PQ'GH$"/B%$"#':%)*+ ,-,O)+2%#1

11. LATERAL and Multi-Source Top-N
Sort/Reduce
Join
everything
#9P9,&1,9P<72QR SOS&AC?G7-O8
TU&!CA,&1,9P<72QR SOS&AC?G7-O8
&&&!CA,&+<,VCEW&,CDT0&V<HDGCA,&+<PW&QOXM
&&&TU&4HGV&.C9:&1,9P<72QQ YOO&AC?G7ZO[ O2Z8
&&&&&&TU&!<&!FH:&C:&GBJGFA9D,9C:G&G
&&&&&&&&&1,9P<7QRZ&AC?G7YO8
&&&&&&TU&4HGV&1,9P<7-O] ZYR&AC?G7-O^S8
&&&&&&&&&TU&!<&!FH:&C:&:<?G&:
&&&&&&&&&&&&1,9P<7Z- 2-Y&AC?G7-O^S8
_;H::9:I&,9P<W&O52Z]&PG
"6<FB,9C:&,9P<W&2QR SOS52R-&PG
Why
producing
900k rows...
...when there
are only 80
subscriptions?

12. LATERAL and Multi-Source Top-N
Sort/Reduce
Join
everything
#9P9,&1,9P<72QR SOS&AC?G7-O8
TU&!CA,&1,9P<72QR SOS&AC?G7-O8
&&&!CA,&+<,VCEW&,CDT0&V<HDGCA,&+<PW&QOXM
&&&TU&4HGV&.C9:&1,9P<72QQ YOO&AC?G7ZO[ O2Z8
&&&&&&TU&!<&!FH:&C:&GBJGFA9D,9C:G&G
&&&&&&&&&1,9P<7QRZ&AC?G7YO8
&&&&&&TU&4HGV&1,9P<7-O] ZYR&AC?G7-O^S8
&&&&&&&&&TU&!<&!FH:&C:&:<?G&:
&&&&&&&&&&&&1,9P<7Z- 2-Y&AC?G7-O^S8
_;H::9:I&,9P<W&O52Z]&PG
"6<FB,9C:&,9P<W&2QR SOS52R-&PG
Only the 10 most
recent per subscription,
you need.

13. !"#"$%&:5'
&&()*+&GBJGFA9D,9C:G&G
&&.*/0&#@%")@#&1!"#"$%&'
&&&&&&&&&&&&&&&&&&()*+&:<?G&:
&&&&&&&&&&&&&&&&&34")"&:5,CD9F&7&G5,CD9F
&&&&&&&&&&&&&&&&&'%($%&)*&/,6-7.879&($12
&&&&&&&&&&&&&&&&&!343#&:;
&&&&&&&&&&&&&&&8&,CD=:<?G&*0&1,AB<8
&34")"&G5BG<A=9E&7&K
&*)L")&MN&:5FA<H,<E&L"!$
&#/+/%&-O
LATERAL and Multi-Source Top-N

14. #9P9,&1,9P<725]YY&AC?G7-O8
TU&!CA,&1,9P<725]YS&AC?G7-O8
&&&TU&0<G,<E&#CCD&1,9P<725QQZ&-<=>?@;;8
&&&&&&TU&/:E<6&*:;`&!FH:&BG9:I&DX&C:&G&&&
&&&&&&&&&1,9P<7O5O]2&AC?G7YO8
&&&&&&TU&#9P9,
&&&&&&&&&1,9P<7O5O2S&AC?G7-O&;CCDG7YO8
&&&&&&&&&TU&/:E<6&!FH:&MHFX?HAE
&&&&&&&&&&&&BG9:I&:<?G=,CD9F=,G=9E&C:&:&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
_;H::9:I&,9P<W&O5-R-&PG
"6<FB,9C:&,9P<W&25[-Z&PG
LATERAL and Multi-Source Top-N
About
100 000 times
faster
Limited to 10
times # of
subscriptions

15. LATERAL in an Nutshell
#@%")@# is the "for each" loop of SQL
#@%")@# plays well with outer joins
#@%")@# is an optimization Super-Power
#@%")@# handy to join table functions

16. LATERAL Availability (SQL:1999)

17. &'#(
(Common Table Expressions)

18. WITH Before SQL:99
Nested queries are hard to read:
!"#"$%&a
&&()*+&1!"#"$%&a
&&&&&&&&&&()*+&,-
&&&&&&&&&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&&&&&&&&&8&H&*0&1a8
&&&&&&&8&J
&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&8&F&*0&1a8

19. Understand
this first
WITH Before SQL:99
Nested queries are hard to read:
!"#"$%&a
&&()*+&1!"#"$%&a
&&&&&&&&&&()*+&,-
&&&&&&&&&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&&&&&&&&&8&H&*0&1a8
&&&&&&&8&J
&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&8&F&*0&1a8

20. WITH Before SQL:99
Then this...
Nested queries are hard to read:
!"#"$%&a
&&()*+&1!"#"$%&a
&&&&&&&&&&()*+&,-
&&&&&&&&&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&&&&&&&&&8&H&*0&1a8
&&&&&&&8&J
&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&8&F&*0&1a8

21. WITH Before SQL:99
Then this...
Nested queries are hard to read:
!"#"$%&a
&&()*+&1!"#"$%&a
&&&&&&&&&&()*+&,-
&&&&&&&&&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&&&&&&&&&8&H&*0&1a8
&&&&&&&8&J
&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&8&F&*0&1a8

22. WITH Before SQL:99
Finally the first line makes sense
Nested queries are hard to read:
!"#"$%&a
&&()*+&1!"#"$%&a
&&&&&&&&&&()*+&,-
&&&&&&&&&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&&&&&&&&&8&H&*0&1a8
&&&&&&&8&J
&&.*/0&1!"#"$%&a&()*+&a
&&&&&&&8&F&*0&1a8

23. CTEs are statement-scoped views:
3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
WITH Since SQL:99

24. CTEs are statement-scoped views:
3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
Keyword
WITH Since SQL:99

25. CTEs are statement-scoped views:
3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
WITH Since SQL:99
Name of CTE and (here
optional) column names

26. CTEs are statement-scoped views:
3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
WITH Since SQL:99
Definition

27. CTEs are statement-scoped views:
3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
WITH Since SQL:99
Introduces
another CTE
Don't repeat
WITH

28. CTEs are statement-scoped views:
3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
WITH Since SQL:99

29. CTEs are statement-scoped views:
3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
WITH Since SQL:99
May refer to
previous CTEs

30. 3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
&F&1a8
@!&1!"#"$%&a&()*+&a8
!"#"$%&a
&&()*+&J&.*/0&F&*0&1a8
WITH Since SQL:99
Third CTE

31. 3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
&F&1a8
@!&1!"#"$%&a&()*+&a8
!"#"$%&a
&&()*+&J&.*/0&F&*0&1a8
WITH Since SQL:99
No comma!

32. 3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
&F&1a8
@!&1!"#"$%&a&()*+&a8
!"#"$%&a
&&()*+&J&.*/0&F&*0&1a8
WITH Since SQL:99
Main query

33. CTEs are statement-scoped views:
3/%4
&H&1F-b&F2b&FQ8
@!&1!"#"$%&F-b&F2b&FQ&()*+&a8b
&J&1F]b&a8
@!&1!"#"$%&F]b&a
&&&&&&()*+&,-
&&&&&&.*/0&H
&&&&&&&&*0&1a8
&&&8b
&F&1a8
@!&1!"#"$%&a&()*+&a8
!"#"$%&a
&&()*+&J&.*/0&F&*0&1a8
WITH Since SQL:99
Read
top down

34. WITH in an Nutshell
3/%4 are the "private methods" of SQL
3/%4 views can be referred to multiple times
3/%4 allows chaining instead of nesting
3/%4 is allowed where !"#"$% is allowed
/0!")%&/0%*&,J;
3/%4&555&!"#"$%&555

35. $%"&!FH:&C:&F,<
&1AC?G7RQSO8
&(9;,<AW&,CD9F&7&-
&$%"&F,<
&TU&!<&!FH:&C:&:<?G
&&&&1AC?G7-OOOOOO-8
WITH PostgreSQL Particularities
In PostgreSQL 3/%4 views are more like
materialized views:
3/%4&F,<&@!
1!"#"$%&'
&&&()*+&:<?G8
!"#"$%&'&
&&()*+&F,<
&34")"&,CD9F7-

36. $%"&!FH:&C:&F,<
&1AC?G7RQSO8
&(9;,<AW&,CD9F&7&-
&$%"&F,<
&TU&!<&!FH:&C:&:<?G
&&&&1AC?G7-OOOOOO-8
WITH PostgreSQL Particularities
In PostgreSQL 3/%4 views are more like
materialized views:
3/%4&F,<&@!
1!"#"$%&'
&&&()*+&:<?G8
!"#"$%&'&
&&()*+&F,<
&34")"&,CD9F7-

37. $%"&!FH:&C:&F,<
&1AC?G7RQSO8
&(9;,<AW&,CD9F&7&-
&$%"&F,<
&TU&!<&!FH:&C:&:<?G
&&&&1AC?G7-OOOOOO-8
WITH PostgreSQL Particularities
In PostgreSQL 3/%4 views are more like
materialized views:
3/%4&F,<&@!
1!"#"$%&'
&&&()*+&:<?G8
!"#"$%&'&
&&()*+&F,<
&34")"&,CD9F7-
CTE
doesn't
know about
the outer
filter

38. Normal views and inline-views support
"predicate pushdown":
!"#"$%&'
&&()*+&1
&&!"#"$%&'
&&&&()*+&:<?G
&&8&:
34")"&,CD9F7-c
M9,PHD&4<HD&!FH:
C:&:<?G&1AC?G7RQSO8
TUM9,PHD&/:E<6&!FH:
&&C:&9E6&1AC?G7RQSO8
&&$C:EW&,CD9F7-
WITH PostgreSQL Particularities

39. PostgreSQL 9.1+ allows /0!")%, d_L@%"
and L"#"%" within 3/%4:
3/%4&E<;<,<E=AC?G&@!&1
&&&L"#"%"&()*+&GCBAF<
&&&)"%d)0/0e&'
8
/0!")%&/0%*&E<G,9:H,9C:
!"#"$%&'&()*+&E<;<,<E=AC?Gc
WITH PostgreSQL Particularities

40. WITH Availability (SQL:99)

41. &'#()%$*+%,'-$
(Common Table Expressions)

42. WITH RECURSIVE Before SQL:99

43. (This page is intentionally left blank)
WITH RECURSIVE Before SQL:99

44. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
Keyword

45. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
Column list
mandatory here

46. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
Executed first

47. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
Result
sent there

48. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
Result
visible
twice

49. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
&:&
TTT
&-
&2
&Q
1Q&AC?G8
Once it becomes
part of
the final
result

50. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
&:&
TTT
&-
&2
&Q
1Q&AC?G8
Second
leg of
UNION
is
executed

51. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
&:&
TTT
&-
&2
&Q
1Q&AC?G8
Result
sent there
again

52. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
&:&
TTT
&-
&2
&Q
1Q&AC?G8

53. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
&:&
TTT
&-
&2
&Q
1Q&AC?G8
It's a
loop!

54. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
&:&
TTT
&-
&2
&Q
1Q&AC?G8
n=3
doesn't
match

55. Recursive common table expressions may refer to
themselves in the second leg of a d0/*0&f@##g:
3/%4&)"$d)!/h"&F,<&1:8
&&@!&1!"#"$%&-
&&&&&&&d0/*0&@##
&&&&&&!"#"$%&:i-
&&&&&&&&()*+&F,<
&&&&&&&34")"&:&j&Q8
!"#"$%&'&()*+&F,<c
WITH RECURSIVE Since SQL:99
&:&
TTT
&-
&2
&Q
1Q&AC?G8
n=3
doesn't
match
Loop
terminates

56. WITH RECURSIVE Use Cases
• Row generators (previous example)
(I<:<AH,<=G<A9<G18 is proprietary)
• Processing graphs
(don't forget the cycle detection!)
• Generally said: Loops that...
‣ ... pass data to the next iteration
‣ ... need a "dynamic" abort condition

57. WITH RECURSIVE in a Nutshell
3/%4&)"$d)!/h" is the ?V9;< of SQL
3/%4&)"$d)!/h" "supports" infinite loops
(not in SQL Server where +@k)"$d)!/*0 is limited to 32767)
Except PostgreSQL, databases generally
don't require the )"$d)!/h" keyword

58. WITH RECURSIVE Availability

59. SQL:2003

60. !"#$%&

61. Pivot table: Years on the Y asis, Month on X axis:
!"#"$%&'"()*&
!"#$%&!'()*'+(#,+-*(.(/
(((((((((-*'+(01230('4!'(5('+67(8&+*
!+,-$(!"&./"0&,10%/&2&3
&&&&&&&&&%/"0&45674&"#!"&8&"09:&;"<*=
&&;)1,&4567>?5@5
&A)1+B&<'&'"()
FILTER Before SQL:2003

62. SQL:2003 has !"#$%&:
'%#%($)*%+&,
!"#$%&'(%)*+,-./0*$12/0/*#34.2*5*6)*7849
'-./012304)!"#$%&)/56%&%).78$6)9):4)!%;,
<
))!&7.)0123=>1?1
)@&7-A);*)*%+&B
FILTER Since SQL:2003

63. FILTER Availability (SQL:2003)

64. .-$%
and
/"%#'#'.0)12

65. Show percentage of department salary:
3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:,
&&@!&1!"#"$%&E<Db&!d+1GH;HA`8&,C,H;
&&&&&&&&()*+&<PD
&&&&&&&e)*d_&MN&E<D8
!"#"$%&E<Db&<PD=9Eb&GH;HA`b
&&&&&&&GH;HA`l,G5,C,H;'-OO&mn&Co&E<Dm
&&()*+&<PD
&&.*/0&,C,H;=GH;HA`=J`=E<DHA,P<:,&,G
&&&&*0&1<PD5E<D&7&,G5E<D8
&34")"&<PD5E<D&7&K
OVER Before SQL:2003

66. Show percentage of department salary:
3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:,
&&@!&1!"#"$%&E<Db&!d+1GH;HA`8&,C,H;
&&&&&&&&()*+&<PD
&&&&&&&e)*d_&MN&E<D8
!"#"$%&E<Db&<PD=9Eb&GH;HA`b
&&&&&&&GH;HA`l,G5,C,H;'-OO&mn&Co&E<Dm
&&()*+&<PD
&&.*/0&,C,H;=GH;HA`=J`=E<DHA,P<:,&,G
&&&&*0&1<PD5E<D&7&,G5E<D8
&34")"&<PD5E<D&7&K
OVER Before SQL:2003

67. Show percentage of department salary:
3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:,
&&@!&1!"#"$%&E<Db&!d+1GH;HA`8&,C,H;
&&&&&&&&()*+&<PD
&&&&&&&e)*d_&MN&E<D8
!"#"$%&E<Db&<PD=9Eb&GH;HA`b
&&&&&&&GH;HA`l,G5,C,H;'-OO&mn&Co&E<Dm
&&()*+&<PD
&&.*/0&,C,H;=GH;HA`=J`=E<DHA,P<:,&,G
&&&&*0&1<PD5E<D&7&,G5E<D8
&34")"&<PD5E<D&7&K
OVER Before SQL:2003

68. Show percentage of department salary:
3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:,
&&@!&1!"#"$%&E<Db&!d+1GH;HA`8&,C,H;
&&&&&&&&()*+&<PD
&&&&&&&e)*d_&MN&E<D8
!"#"$%&E<Db&<PD=9Eb&GH;HA`b
&&&&&&&GH;HA`l,G5,C,H;'-OO&mn&Co&E<Dm
&&()*+&<PD
&&.*/0&,C,H;=GH;HA`=J`=E<DHA,P<:,&,G
&&&&*0&1<PD5E<D&7&,G5E<D8
&34")"&<PD5E<D&7&K
OVER Before SQL:2003
WITH intermezzo

69. Show percentage of department salary:
3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:,
&&@!&1!"#"$%&E<Db&!d+1GH;HA`8&,C,H;
&&&&&&&&()*+&<PD
&&&&&&&e)*d_&MN&E<D8
!"#"$%&E<Db&<PD=9Eb&GH;HA`b
&&&&&&&GH;HA`l,G5,C,H;'-OO&mn&Co&E<Dm
&&()*+&<PD
&&.*/0&,C,H;=GH;HA`=J`=E<DHA,P<:,&,G
&&&&*0&1<PD5E<D&7&,G5E<D8
&34")"&<PD5E<D&7&K
OVER Before SQL:2003

70. e)*d_&MN&=
L/!%/0$%
+
Aggregates
OVER Before SQL:2003

71. Build aggregates without e)*d_&MN:
!"#"$%&E<Db&<PD=9Eb&GH;HA`b
&&&&&&&GH;HA`l1A4B>.C.-DE
&&&&&&&&&&&&&&'F$%BG"%#3#3'H&)*&97+E
&&&&&&&&&&&&&'&-OO&mn&Co&E<Dm
&&()*+&<PD
OVER Since SQL:2003

72. OVER How It Works
E<D GH;HA`
- -OOO ROOO
22 -OOO ROOO
22 -OOO ROOO
QQQ -OOO ROOO
QQQ -OOO ROOO
QQQ -OOO ROOO
!"#"$%&E<Db&
&&&&&&&GH;HA`b
&&&&&&&!d+1GH;HA`8
&&&&&&&*h")&18
&&()*+&<PDc

73. OVER How It Works
E<D GH;HA`
- -OOO ROOO
22 -OOO ROOO
22 -OOO ROOO
QQQ -OOO ROOO
QQQ -OOO ROOO
QQQ -OOO ROOO
!"#"$%&E<Db&
&&&&&&&GH;HA`b
&&&&&&&!d+1GH;HA`8
&&&&&&&*h")&18
&&()*+&<PDc

74. OVER How It Works
E<D GH;HA`
- -OOO ROOO
22 -OOO ROOO
22 -OOO ROOO
QQQ -OOO ROOO
QQQ -OOO ROOO
QQQ -OOO ROOO
!"#"$%&E<Db&
&&&&&&&GH;HA`b
&&&&&&&!d+1GH;HA`8
&&&&&&&*h")&18
&&()*+&<PDc

75. %&E<Db&
&&GH;HA`b
&&!d+1GH;HA`8
&&*h")1_@)%/%/*0&MN&E<D8
+&<PDc
E<D GH;HA` ,G
- -OOO -OOO
22 -OOO 2OOO
22 -OOO 2OOO
QQQ -OOO QOOO
QQQ -OOO QOOO
QQQ -OOO QOOO
OVER How It Works

76. %&E<Db&
&&GH;HA`b
&&!d+1GH;HA`8
&&*h")1_@)%/%/*0&MN&E<D8
+&<PDc
E<D GH;HA` ,G
- -OOO -OOO
22 -OOO 2OOO
22 -OOO 2OOO
QQQ -OOO QOOO
QQQ -OOO QOOO
QQQ -OOO QOOO
OVER How It Works

77. %&E<Db&
&&GH;HA`b
&&!d+1GH;HA`8
&&*h")1_@)%/%/*0&MN&E<D8
+&<PDc
E<D GH;HA` ,G
- -OOO -OOO
22 -OOO 2OOO
22 -OOO 2OOO
QQQ -OOO QOOO
QQQ -OOO QOOO
QQQ -OOO QOOO
OVER How It Works

78. OVER in a Nutshell
*h") may follow any aggregate function
*h") defines which rows are visible at each row
(it does not limit the result in any way)
*h")18 makes all rows visible at every row
*h")1_@)%/%/*0&MN x) segregates like e)*d_&MN

79. .-$%
and
.%3$%)12

80. OVER Before SQL:2003
Calculating a running total:
!"#"$%&,69Eb&>H;B<b
&&&&&&&1!"#"$%&!d+1>H;B<8
&&&&&&&&&&()*+&,AH:GHF,9C:G&,62
&&&&&&&&&34")"&HF:,&7&K
&&&&&&&&&&&@0L&,625,69E&j7&,6-5,69E8&JH;
&&()*+&,AH:GHF,9C:G&,6-
&34")"&HF:,&7&K
&*)L")&MN&,69E

81. OVER Before SQL:2003
Calculating a running total:
!"#"$%&,69Eb&>H;B<b
&&&&&&&1!"#"$%&!d+1>H;B<8
&&&&&&&&&&()*+&,AH:GHF,9C:G&,62
&&&&&&&&&34")"&HF:,&7&K
&&&&&&&&&&&@0L&,625,69E&j7&,6-5,69E8&JH;
&&()*+&,AH:GHF,9C:G&,6-
&34")"&HF:,&7&K
&*)L")&MN&,69E

82. OVER Before SQL:2003
Calculating a running total:
!"#"$%&,69Eb&>H;B<b
&&&&&&&1!"#"$%&!d+1>H;B<8
&&&&&&&&&&()*+&,AH:GHF,9C:G&,62
&&&&&&&&&34")"&HF:,&7&K
&&&&&&&&&&&@0L&,625,69E&j7&,6-5,69E8&JH;
&&()*+&,AH:GHF,9C:G&,6-
&34")"&HF:,&7&K
&*)L")&MN&,69E

83. OVER Before SQL:2003
Calculating a running total:
!"#"$%&,69Eb&>H;B<b
&&&&&&&1!"#"$%&!d+1>H;B<8
&&&&&&&&&&()*+&,AH:GHF,9C:G&,62
&&&&&&&&&34")"&HF:,&7&K
&&&&&&&&&&&@0L&,625,69E&j7&,6-5,69E8&JH;
&&()*+&,AH:GHF,9C:G&,6-
&34")"&HF:,&7&K
&*)L")&MN&,69E

84. OVER Before SQL:2003
Calculating a running total:
!"#"$%&,69Eb&>H;B<b
&&&&&&&1!"#"$%&!d+1>H;B<8
&&&&&&&&&&()*+&,AH:GHF,9C:G&,62
&&&&&&&&&34")"&HF:,&7&K
&&&&&&&&&&&@0L&,625,69E&j7&,6-5,69E8&JH;
&&()*+&,AH:GHF,9C:G&,6-
&34")"&HF:,&7&K
&*)L")&MN&,69E

85. OVER Before SQL:2003
Before SQL:2003 running totals were awkward:
‣ Requires a scalar sub-select or self-join
‣ Poor maintainability (reparative clauses)
‣ Poor performance
The only real answer was:
Do it in the application

86. With SQL:2003 you can narrow the window:
!"#"$%&,69Eb&>H;B<b
&&&&&&&!d+1>H;B<8
&&&&&&&*h")1'%($%&)*&8IJ9
&&&&&&&&&&&&%'K1
&&&&&&&&&&&&)$#K$$H&AH)'AH($(&G%$2$(3HL
&&&&&&&&&&&&&&&&"H(&2A%%$H#&%'K8&JH;
&&()*+&,AH:GHF,9C:G&,6-
&34")"&HF:,&7&K
&*)L")&MN&,69E
OVER Since SQL:2003

87. With *h")&1*)L")&MN&a8 a new type of
functions makes sense:
‣ )*3=0d+M")
‣ Ranking functions:&
)@0pb&L"0!"=)@0pb&_")$"0%=)@0pb
$d+"=L/!%
OVER Since SQL:2003

88. OVER Availability (SQL:2003)

89. !"#$"%&'()*+

90. WITHIN GROUP Before SQL:2003
Getting the median:
!"#"$%&'()*+,
&&-./0&'+1+&'(
&&2/34&'+1+&'5
&&&&/4&6'()*+,&7&'5)*+,
&&&&&&&/.&6'()*+,8'5)*+,&94:&'();'7'5);'<<
&=./>?&@A&'()*+,
B9C34=&DEFG16H<&8&
&&&&&&&6!"#"$%&-#//.6$/>4%6H<I5<
&&&&&&&&&&-./0&'+1+<

91. WITHIN GROUP Since SQL:2003
SQL:2003 introduced ordered-set functions...
!"#"$%&'"($")%*#"+,*!$-./01
&&&&&&&2*%3*)&4(56'&-5(,"(&78&9:;1
&&<(5=&>:?:
...and hypothetical-set functions to say which rank
a hypothetical row would have:
&!"#"$%&(@)A-BCD1
&&&&&&&&2*%3*)&4(56'&-5(,"(&78&9:;1
&&&<(5=&>:?:
Median
Which value?

92. WITHIN GROUP Availability

93. SQL:2008

94. .-$%

95. Calculate the difference to a previous row:
3/%4&:BPJ<A<E=EH,H&@!&1
&!"#"$%&'b
&&&&&&&&)*3=0d+M")18&*h")1*)L")&MN&68&A:
&&&()*+&EH,H8&
!"#"$%&FBA5'b&FBA5JH;H:F<TDA<>5JH;H:F<
&&()*+&&&&&&:BPJ<A<E=EH,H&FBA
&&#"(%&.*/0&:BPJ<A<E=EH,H&DA<>
&&&&*0&1FBA5A:&7&DA<>5A:T-8
OVER Before SQL:2008

96. Calculate the difference to a previous row:
3/%4&:BPJ<A<E=EH,H&@!&1
&!"#"$%&'b
&&&&&&&&)*3=0d+M")18&*h")1*)L")&MN&68&A:
&&&()*+&EH,H8&
!"#"$%&FBA5'b&FBA5JH;H:F<TDA<>5JH;H:F<
&&()*+&&&&&&:BPJ<A<E=EH,H&FBA
&&#"(%&.*/0&:BPJ<A<E=EH,H&DA<>
&&&&*0&1FBA5A:&7&DA<>5A:T-8
OVER Before SQL:2008

97. SQL:2008 can access other rows directly:
!"#"$%&'b&JH;H:F<&T&#@e1JH;H:F<8
&&&&&&&&&&&&&&&&&&&&*h")1*)L")&MN&68
&&()*+&EH,H
Available functions:
&#"@L&l&#@e
&(/)!%=h@#d"&l&#@!%=h@#d"
&0%4=h@#d"1FC;b&:8&()*+&(/)!%l#@!%
&&&&&&&&&&&&&&&&&&&)"!_"$%l/e0*)"&0d##!
OVER Since SQL:2008
Not supported
by PostgreSQL
(as of 9.4)

98. OVER Availability (SQL:2008)

99. 4$#*()4'%,#

100. Limit the number of selected rows:
!"#"$%&'
&&()*+&1!"#"$%&'b
&&&&&&&&)*3=0d+M")18&*h")1*)L")&MN&68&A:
&&&()*+&EH,H8&:BPJ<A<E=EH,H
&34")"&A:&j7-O
FETCH FIRST Before SQL:2008

101. Limit the number of selected rows:
!"#"$%&'
&&()*+&1!"#"$%&'b
&&&&&&&&)*3=0d+M")18&*h")1*)L")&MN&68&A:
&&&()*+&EH,H8&:BPJ<A<E=EH,H
&34")"&A:&j7-O
FETCH FIRST Before SQL:2008
PostgreSQL
does not optimize
this properly!

102. Limit the number of selected rows:
!"#"$%&'
&&()*+&1!"#"$%&'b
&&&&&&&&)*3=0d+M")18&*h")1*)L")&MN&68&A:
&&&()*+&EH,H8&:BPJ<A<E=EH,H
&34")"&A:&j7-O
FETCH FIRST Before SQL:2008
Dammit!
Let's take
LIMIT
(or TOP)

103. SQL:2008 has ("%$4&(/)!%&:&)*3!&*0#N:
!"#"$%&'
&&()*+&EH,H
&*)L")&MN&6
&("%$4&(/)!%&-O&)*3!&*0#N
FETCH FIRST Since SQL:2008

104. FETCH FIRST Availability

105. SQL:2011

106. .44,$#

107. Skip 10 rows, then deliver only the next 10:
!"#"$%&'
&&()*+&1!"#"$%&'b
&&&&&&&&)*3=0d+M")18&*h")1*)L")&MN&68&A:
&&&()*+&EH,H
&&("%$4&(/)!%&2O&)*3!&*0#N
8&:BPJ<A<E=EH,H
&34")"&A:&U&-O
OFFSET Before SQL:2011

108. SQL:2011 introduced *((!"%, unfortunately:
!"#"$%&'
&&()*+&EH,H
&*)L")&MN&6
'MM1$#&:;&%'K1
("%$4&0"k%&-O&)*3!&*0#N
OFFSET Since SQL:2011

109. OFFSET is EVIL
http://use-the-index-luke.com/no-offset

110. OFFSET Availability (SQL:2011)

111. &'#(.+#).-$%!"/,

112. Prior SQL:2011 it was not possible to define
constraints that avoid overlapping periods.
Workarounds are possible,
but no fun: $)"@%"&%)/ee")
WITHOUT OVERLAPS Before SQL:2011
id begin end
1 8:00 9:00
1 9:00 11:00
1 10:00 12:00

113. SQL:2011 introduced temporal and bi-temporal
features —e.g., for constraints:
_)/+@)N&p"N&19Eb&+7-J<9&K3#N'A#&'F$%!"G18
PostgreSQL 9.2 introduced range types and
"exclusive constraints" which can accomplish the
same effect:
"k$#dL"&d!/0e&I9G,
&&&&&&&&19E&3/%4&7b&+7-J<9&K3#N&OO8
WITHOUT OVERLAPS Since SQL:2011

114. SQL:2011 goes far beyond 3/%4*d%&*h")#@_!.
Please read these papers to get the idea:
Temporal features in SQL:2011
http://cs.ulb.ac.be/public/_media/teaching/infoh415/tempfeaturessql2011.pdf
What's new in SQL:2011?
http://www.sigmod.org/publications/sigmod-record/1203/pdfs/10.industry.zemke.pdf
Temporal/Bi-Temporal SQL

115. WITHOUT OVERLAPS Availability

116. About @MarkusWinand
Tuning developers for
high SQL performance
Training & tuning:
http://winand.at/
Author of:
http://sql-performance-explained.com/
Geeky blog:
http://use-the-index-luke.com