Still using. Windows 3.1? So why stick to SQL-92? Modern SQL in

Transcription

1 Still using Windows 3.1? So why stick to SQL-92? Modern SQL in

2 SQL:1999

3 !"#$%"!

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

5 LATERAL Before SQL:1999 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 Belongs there

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

7 But WHY?

8 LATERAL and Top-N per Group Apply #/+/% per row from previous table:!"#"$%&,cd=dacebf,g5' &&()*+&FH,<ICA9<G&F &&&&&&&&&&&&&&&&&&()*+&DACEBF,G&D &&&&&&&&&&&&&&&&&34")"&D5FH,&7&F5FH, &&&&&&&&&&&&&&&&&'%($%&)*&+,-./0&($12 &&&&&&&&&&&&&&&&&!343#&5 &&&&&&&&&&&&&&&8&,CD=DACEBF,G

9 LATERAL and Multi-Source Top-N 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

10 LATERAL and Multi-Source Top-N!"#"$%&$"#'()*+,-,%./01(2-3 Sort/Reduce 45%6/.$%&$"#'()*+,-,%./01(2-3 %%%6/.$%7'$8/9:%$/;4<%8'=;1/.$%7'#:%*->? C--%./01(D-E -)D3 %%%%%%45%6'F%6G=B%/B%1HI1G.";$"/B1%1 Join everything %%%%%%%%%&$"#'(*+D%./01(C-3 DC+%./01(2-K,3 %%%%%%%%%45%6'F%6G=B%/B%B'01%B %%%%%%%%%%%%&$"#'(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 #9P9,&1,9P<72QR SOS&AC?G7-O8 TU&!CA,&1,9P<72QR SOS&AC?G7-O8 Why producing 900k rows... Sort/Reduce &&&!CA,&+<,VCEW&,CDT0&V<HDGCA,&+<PW&QOXM &&&TU&4HGV&.C9:&1,9P<72QQ YOO&AC?G7ZO[ O2Z8 &&&&&&TU&!<\&!FH:&C:&GBJGFA9D,9C:G&G Join everything &&&&&&&&&1,9P<7QRZ&AC?G7YO8 &&&&&&TU&4HGV&1,9P<7-O] ZYR&AC?G7-O^S8 &&&&&&&&&TU&!<\&!FH:&C:&:<?G&:...when there are only 80 subscriptions? &&&&&&&&&&&&1,9P<7Z- 2-Y&AC?G7-O^S8 _;H::9:I&,9P<W&O52Z]&PG "6<FB,9C:&,9P<W&2QR SOS52R-&PG

12 LATERAL and Multi-Source Top-N #9P9,&1,9P<72QR SOS&AC?G7-O8 Only the 10 most Sort/Reduce TU&!CA,&1,9P<72QR SOS&AC?G7-O8 recent per subscription, you need. &&&!CA,&+<,VCEW&,CDT0&V<HDGCA,&+<PW&QOXM &&&TU&4HGV&.C9:&1,9P<72QQ YOO&AC?G7ZO[ O2Z8 &&&&&&TU&!<\&!FH:&C:&GBJGFA9D,9C:G&G Join everything &&&&&&&&&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

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

14 LATERAL and Multi-Source Top-N #9P9,&1,9P<725]YY&AC?G7-O8 TU&!CA,&1,9P<725]YS&AC?G7-O8 &&&&&&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:&:&& times _;H::9:I&,9P<W&O5-R-&PG "6<FB,9C:&,9P<W&25[-Z&PG Limited to 10 times # of subscriptions About faster

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

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

21 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 Then this... &&&&&&&8&F&*0&1a8

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

23 WITH Since SQL:99 CTEs are statement-scoped views: 3/%4 &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b

24 WITH Since SQL:99 CTEs are statement-scoped views: Keyword 3/%4 &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b

25 WITH Since SQL:99 CTEs are statement-scoped views: 3/%4 Name of CTE and (here optional) column names &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b

26 WITH Since SQL:99 CTEs are statement-scoped views: 3/%4 &H&1F-b&F2b&FQ8 &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b

27 WITH Since SQL:99 CTEs are statement-scoped views: 3/%4 &H&1F-b&F2b&FQ8 Introduces another Don't repeat WITH &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b

28 WITH Since SQL:99 CTEs are statement-scoped views: 3/%4 &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b

29 WITH Since SQL:99 CTEs are statement-scoped views: 3/%4 &&&&&&()*+&,- May refer to &&&&&&.*/0&H previous CTEs &&&&&&&&*0&1a8 &&&8b

30 3/%4 &H&1F-b&F2b&FQ8 WITH Since &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b Third CTE &&()*+&J&.*/0&F&*0&1a8

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

32 3/%4 &H&1F-b&F2b&FQ8 WITH Since &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b Main query &&()*+&J&.*/0&F&*0&1a8

33 WITH Since SQL:99 CTEs are statement-scoped views: 3/%4 &&&&&&()*+&,- &&&&&&.*/0&H &&&&&&&&*0&1a8 &&&8b &&()*+&J&.*/0&F&*0&1a8 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 WITH PostgreSQL Particularities In PostgreSQL 3/%4 views are more like materialized views: $%"&!FH:&C:&F,< &1AC?G7RQSO8 &(9;,<AW&,CD9F&7&- &$%"&F,< &TU&!<\&!FH:&C:&:<?G &&&&1AC?G7-OOOOOO-8 1!"#"$%&' &&&()*+&:<?G8!"#"$%&'& &&()*+&F,< &34")"&,CD9F7-

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

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

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

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

40 WITH Availability (SQL:99)

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

42 WITH RECURSIVE Before SQL:99

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

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

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

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

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

48 WITH RECURSIVE Since SQL:99 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&@## &&&&&&!"#"$%&:i- &&&&&&&&()*+&F,< &&&&&&&34")"&:&j&Q8 Result visible twice!"#"$%&'&()*+&f,<c

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

50 WITH RECURSIVE Since SQL:99 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 Second leg of UNION is executed &:& TTT &- &2 &Q 1Q&AC?G8

51 WITH RECURSIVE Since SQL:99 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 Result sent there again &:& TTT &- &2 &Q 1Q&AC?G8

52 WITH RECURSIVE Since SQL:99 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 &:& TTT &- &2 &Q 1Q&AC?G8

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

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

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

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 FILTER Before SQL:2003 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&<'&'"()

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

63 FILTER Availability (SQL:2003)

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

65 OVER Before SQL:2003 Show percentage of department salary: 3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:, &&&&&&&&()*+&<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

66 OVER Before SQL:2003 Show percentage of department salary: 3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:, &&&&&&&&()*+&<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

67 OVER Before SQL:2003 Show percentage of department salary: 3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:, &&&&&&&&()*+&<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

68 OVER Before SQL:2003 WITH intermezzo Show percentage of department salary: 3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:, &&&&&&&&()*+&<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

69 OVER Before SQL:2003 Show percentage of department salary: 3/%4&,C,H;=GH;HA`=J`=E<DHA,P<:, &&&&&&&&()*+&<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

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

71 OVER Since SQL:2003 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

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

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

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

75 OVER How It Works E<D GH;HA`,G &E<Db& &GH;HA`b &!d+1gh;ha`8 &<PDc - -OOO -OOO 22 -OOO 2OOO 22 -OOO 2OOO QQQ -OOO QOOO QQQ -OOO QOOO QQQ -OOO QOOO

76 OVER How It Works E<D GH;HA`,G &E<Db& &GH;HA`b &!d+1gh;ha`8 &<PDc - -OOO -OOO 22 -OOO 2OOO 22 -OOO 2OOO QQQ -OOO QOOO QQQ -OOO QOOO QQQ -OOO QOOO

77 OVER How It Works E<D GH;HA`,G &E<Db& &GH;HA`b &!d+1gh;ha`8 &<PDc - -OOO -OOO 22 -OOO 2OOO 22 -OOO 2OOO QQQ -OOO QOOO QQQ -OOO QOOO QQQ -OOO QOOO

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 OVER Since SQL:2003 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

87 OVER Since SQL:2003 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/!%

88 OVER Availability (SQL:2003)

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

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

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

92 WITHIN GROUP Availability

93 SQL:2008

94 .-$%

95 OVER Before SQL:2008 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

96 OVER Before SQL:2008 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

97 OVER Since SQL:2008 SQL:2008 can access other rows &&&&&&&&&&&&&&&&&&&&*h")1*)l")&mn&68 &&()*+&EH,H Available functions: Not supported by PostgreSQL (as of 9.4) &&&&&&&&&&&&&&&&&&&)"!_"$%l/e0*)"&0d##!

98 OVER Availability (SQL:2008)

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

100 FETCH FIRST Before SQL:2008 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

101 FETCH FIRST Before SQL:2008 PostgreSQL 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 does not optimize this properly!

102 FETCH FIRST Before SQL:2008 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 Dammit! Let's take LIMIT (or TOP)

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

104 FETCH FIRST Availability

105 SQL:2011

106 .44,$#

107 OFFSET Before SQL:2011 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

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

109 OFFSET is EVIL

110 OFFSET Availability (SQL:2011)

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

112 WITHOUT OVERLAPS Before SQL:2011 Prior SQL:2011 it was not possible to define constraints that avoid overlapping periods. Workarounds are possible, but no fun: id begin end 1 8:00 9:00 1 9:00 11: :00 12:00

113 WITHOUT OVERLAPS Since SQL:2011 SQL:2011 introduced temporal and bi-temporal features e.g., for constraints: 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

114 Temporal/Bi-Temporal SQL SQL:2011 goes far beyond Please read these papers to get the idea: Temporal features in SQL: What's new in SQL:2011?

115 WITHOUT OVERLAPS Availability

116 Tuning developers for high SQL performance Training & tuning: Author of: Geeky blog: