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}, { "id": "01a0c54d-df0c-72cf-9dee-58de1fee6939", "title": "Calculating mode", "url": "https://explainextended.com/2010/01/18/calculating-mode/", "published_at": "2010-01-18T20:00:32+00:00" }, { "id": "01a0c54d-df0c-72cf-9dee-58de20b31e3a", "title": "Latest visitors", "url": "https://explainextended.com/2010/01/12/latest-visitors/", "published_at": "2010-01-12T20:00:26+00:00" }, { "id": "01a0c54d-df0c-72cf-9dee-58de218b3647", "title": "Happy New Year!", "url": "https://explainextended.com/2009/12/31/happy-new-year/", "published_at": "2009-12-31T20:00:47+00:00" }, { "id": "01a0c54d-df0c-72cf-9dee-58de2222cf53", "title": "Grouping continuous ranges", "url": "https://explainextended.com/2009/12/30/grouping-continuous-ranges/", "published_at": "2009-12-30T20:00:32+00:00" }, { "id": "01a0c54d-df0c-72cf-9dee-58de22e2469b", "title": "Linked lists in MySQL: multiple ordering", "url": "https://explainextended.com/2009/12/29/linked-lists-in-mysql-multiple-ordering/", "published_at": "2009-12-29T20:00:37+00:00" }, { "id": "01a0c54d-df0c-72cf-9dee-58de23831c51", "title": "Oracle: joining timestamps and time intervals", "url": "https://explainextended.com/2009/12/28/oracle-joining-timestamps-and-time-intervals/", "published_at": "2009-12-28T20:00:20+00:00" }, { "id": "01a0c54d-df0c-72cf-9dee-58de2425f029", "title": "Oracle: Selecting records holding group-wise maximum", "url": "https://explainextended.com/2009/12/16/oracle-selecting-records-holding-group-wise-maximum/", "published_at": "2009-12-16T20:00:37+00:00" }, { "id": "01a0c54d-df0c-72cf-9dee-58de24915df0", "title": "SQL Server: Selecting records holding group-wise maximum (with ties)", "url": "https://explainextended.com/2009/12/01/sql-server-selecting-records-holding-group-wise-maximum-with-ties/", "published_at": "2009-12-01T20:00:58+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a46332891f0", "title": "SQL Server: Selecting records holding group-wise maximum", "url": "https://explainextended.com/2009/11/30/sql-server-selecting-records-holding-group-wise-maximum/", "published_at": "2009-11-30T20:00:11+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a46334474d1", "title": "PostgreSQL: Selecting records holding group-wise maximum", "url": "https://explainextended.com/2009/11/26/postgresql-selecting-records-holding-group-wise-maximum/", "published_at": "2009-11-26T20:00:25+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a46340adf4c", "title": "MySQL: Selecting records holding group-wise maximum (resolving ties)", "url": "https://explainextended.com/2009/11/25/mysql-selecting-records-holding-group-wise-maximum-resolving-ties/", "published_at": "2009-11-25T20:00:46+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a4634888f98", "title": "MySQL: Selecting records holding group-wise maximum (on a unique column)", "url": "https://explainextended.com/2009/11/24/mysql-selecting-records-holding-group-wise-maximum-on-a-unique-column/", "published_at": "2009-11-24T20:00:51+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a4634d0dec8", "title": "Recursive CTE’s: PostgreSQL", "url": "https://explainextended.com/2009/11/23/recursive-ctes-postgresql/", "published_at": "2009-11-23T20:00:24+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a4635429ca0", "title": "SQL Server: are the recursive CTE’s really set-based?", "url": "https://explainextended.com/2009/11/18/sql-server-are-the-recursive-ctes-really-set-based/", "published_at": "2009-11-18T20:00:18+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a463605badc", "title": "Selecting most relevant row", "url": "https://explainextended.com/2009/11/17/selecting-most-relevant-row/", "published_at": "2009-11-17T20:00:02+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a46364f734d", "title": "Inverting date ranges: MySQL", "url": "https://explainextended.com/2009/11/12/inverting-date-ranges-mysql/", "published_at": "2009-11-12T20:00:30+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a4636c4b339", "title": "SQL Server: clustered index and ordering", "url": "https://explainextended.com/2009/11/11/sql-server-clustered-index-and-ordering/", "published_at": "2009-11-11T20:00:38+00:00" }, { "id": "01a0c556-5d92-7215-a960-0a46375c4168", "title": "MySQL: average of sums using indexes", "url": "https://explainextended.com/2009/11/10/mysql-average-of-sums-using-indexes/", "published_at": "2009-11-10T20:00:14+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e17d5523", "title": "Inverting date ranges", "url": "https://explainextended.com/2009/11/09/inverting-date-ranges/", "published_at": "2009-11-09T20:00:47+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e1836819", "title": "MySQL ORDER BY / LIMIT performance: late row lookups", "url": "https://explainextended.com/2009/10/23/mysql-order-by-limit-performance-late-row-lookups/", "published_at": "2009-10-23T19:00:50+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e1f4a35b", "title": "Generating row placeholders: SQL Server", "url": "https://explainextended.com/2009/10/21/generating-row-placeholders-sql-server/", "published_at": "2009-10-21T19:00:14+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e28f23e9", "title": "What is entity-relationship model?", "url": "https://explainextended.com/2009/10/18/what-is-entity-relationship-model/", "published_at": "2009-10-18T19:00:46+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e36590f8", "title": "Constraints and the optimizer in SQL Server: FOREIGN KEY", "url": "https://explainextended.com/2009/10/15/constraints-and-the-optimizer-in-sql-server-foreign-key/", "published_at": "2009-10-15T19:00:33+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e41712a5", "title": "Constraints and the optimizer in SQL Server: PRIMARY KEY and UNIQUE", "url": "https://explainextended.com/2009/10/14/constraints-and-the-optimizer-in-sql-server-unique/", "published_at": "2009-10-14T19:00:42+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e4e3f541", "title": "Running root mean square: SQL Server", "url": "https://explainextended.com/2009/10/13/running-root-mean-square-sql-server/", "published_at": "2009-10-13T19:00:45+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e585f863", "title": "Minimum and maximum on bit fields: SQL Server", "url": "https://explainextended.com/2009/10/12/minimum-and-maximum-on-bit-fields-sql-server/", "published_at": "2009-10-12T19:00:20+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e6479592", "title": "Oracle: nested SUM", "url": "https://explainextended.com/2009/10/08/oracle-nested-sum/", "published_at": "2009-10-08T19:00:46+00:00" }, { "id": "01a0c55e-90e6-71a4-ba7a-3ca9e69e41cc", "title": "IN list vs. range condition: MySQL", "url": "https://explainextended.com/2009/10/07/in-list-vs-range-condition-mysql/", "published_at": "2009-10-07T19:00:55+00:00" } ] posts Claim your blog

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2025

Happy New Year: Lisp interpreter in SQL original ↗

31 Dec 2025

2024

Happy New Year: Diffusion Model image generator in about 700 lines of pure SQL original ↗

31 Dec 2024

2023

Happy New Year: GPT in 500 lines of SQL original ↗

31 Dec 2023

2022

Happy New Year: solving the Rubik’s Cube in SQL original ↗

31 Dec 2022

A good first word for Wordle original ↗

27 Jan 2022

2021

Happy New Year: quantum computer emulator in SQL original ↗

31 Dec 2021

2020

Happy New Year: 3D picture of the coronavirus in SQL original ↗

31 Dec 2020

2019

Happy New Year: a stereogram in SQL original ↗

31 Dec 2019

2018

Happy New Year: GIF decoder in SQL original ↗

31 Dec 2018

2017

Happy New Year: Settlers of Catan in SQL original ↗

31 Dec 2017

2016

Happy New Year: the Sultan’s Riddle in SQL original ↗

31 Dec 2016

2015

Happy New Year: Conway’s Game of Life in SQL original ↗

31 Dec 2015

2014

Happy New Year: composing music in SQL original ↗

31 Dec 2014

SQL Server: deleting with self-referential FOREIGN KEY, handling loops original ↗

10 Jul 2014

Top 5 XKCD comics which can illustrate programming questions original ↗

9 Jul 2014

2013

Happy New Year: drawing fractals in SQL original ↗

31 Dec 2013

5 Claims About SQL, Explained original ↗

28 Oct 2013

NULL in SQL: explaining its behavior original ↗

27 Sept 2013

Did You Know You Could Index SUM() and COUNT(): SQL Server Indexed Views, Part 3 original ↗

26 Aug 2013

Storing a Friendship: SQL Server Indexed Views, Part 2 original ↗

14 Aug 2013

10 things in SQL Server (which don’t work as expected)original ↗

19 Jul 2013

Score charts, friendship lists and unique multiple columns: easy with SQL Server’s indexed views original ↗

27 Jun 2013

SQL Server: joining NULL values original ↗

8 May 2013

INSERT … SELECT … OUTPUT …: returning source table data original ↗

25 Mar 2013

Empty row if condition does not match original ↗

3 Jan 2013

2012

Happy New Year: view of Earth from space in SQL original ↗

31 Dec 2012

2011

Happy New Year: drawing snowflakes in SQL original ↗

31 Dec 2011

What’s UNPIVOT good for?original ↗

30 Jun 2011

Shared Plan and Algorithm Network Cache (SPANC)original ↗

1 Apr 2011

MySQL: GROUP BY in UNION original ↗

30 Mar 2011

MySQL: splitting aggregate queries original ↗

28 Mar 2011

Things SQL needs: SERIES()original ↗

18 Feb 2011

Late row lookups: InnoDB original ↗

11 Feb 2011

2010

Happy New Year: drawing clock in SQL original ↗

31 Dec 2010

PostgreSQL: parametrizing a recursive CTE original ↗

24 Dec 2010

10 things in MySQL (that won’t work as expected)original ↗

3 Nov 2010

Mixed ASC/DESC sorting in MySQL original ↗

2 Nov 2010

Correlated LEFT JOIN in a subquery original ↗

20 Oct 2010

OLAP in MySQL: four ways to filter on higher level dimensions original ↗

30 Sept 2010

20 latest unique records original ↗

24 Aug 2010

Questions original ↗

15 Jul 2010

Indexing for ORDER BY / LIMIT original ↗

30 Jun 2010

GROUP_CONCAT in SQL Server original ↗

21 Jun 2010

LEFT JOIN / IS NULL vs. NOT IN vs. NOT EXISTS: nullable columns original ↗

27 May 2010

Things SQL needs: determining range cardinality original ↗

19 May 2010

MAX and MIN on a composite index original ↗

8 May 2010

Things SQL needs: MERGE JOIN that would seek original ↗

7 May 2010

Groups holding highest ranked items original ↗

22 Apr 2010

Hierarchical query in MySQL: limiting parents original ↗

18 Apr 2010

Date ranges: overlapping with priority original ↗

7 Apr 2010

Multiple attributes in a EAV table: GROUP BY vs. NOT EXISTS original ↗

2 Apr 2010

NoSQL original ↗

1 Apr 2010

Bayesian classification original ↗

25 Mar 2010

Greatest N per group: dealing with aggregates original ↗

18 Mar 2010

Aggregates and LEFT JOIN original ↗

5 Mar 2010

SQL Server: deleting with self-referential FOREIGN KEY original ↗

3 Mar 2010

PostgreSQL: using recursive functions in nested sets original ↗

2 Mar 2010

PostgreSQL: nested sets and R-Tree original ↗

1 Mar 2010

Six degrees of separation original ↗

27 Feb 2010

Efficient circle distance testing original ↗

26 Feb 2010

Matching sets: aggregates vs. first miss original ↗

25 Feb 2010

Sargability of monotonic functions: example original ↗

23 Feb 2010

Things SQL needs: sargability of monotonic functions original ↗

19 Feb 2010

Tags in nested sets: efficient indexing original ↗

16 Feb 2010

SQL Server: EXCEPT ALL original ↗

10 Feb 2010

Index search time depends on the value being searched original ↗

4 Feb 2010

Searching for arbitrary portions of a date original ↗

2 Feb 2010

Join on overlapping date ranges original ↗

1 Feb 2010

Aggregates: subqueries vs. GROUP BY original ↗

30 Jan 2010

Counting concurrent sessions original ↗

25 Jan 2010

SQL Server: running totals original ↗

22 Jan 2010

Cumulative values original ↗

20 Jan 2010

Calculating mode original ↗

18 Jan 2010

Latest visitors original ↗

12 Jan 2010

2009

Happy New Year!original ↗

31 Dec 2009

Grouping continuous ranges original ↗

30 Dec 2009

Linked lists in MySQL: multiple ordering original ↗

29 Dec 2009

Oracle: joining timestamps and time intervals original ↗

28 Dec 2009

Oracle: Selecting records holding group-wise maximum original ↗

16 Dec 2009

SQL Server: Selecting records holding group-wise maximum (with ties)original ↗

1 Dec 2009

SQL Server: Selecting records holding group-wise maximum original ↗

30 Nov 2009

PostgreSQL: Selecting records holding group-wise maximum original ↗

26 Nov 2009

MySQL: Selecting records holding group-wise maximum (resolving ties)original ↗

25 Nov 2009

MySQL: Selecting records holding group-wise maximum (on a unique column)original ↗

24 Nov 2009

Recursive CTE’s: PostgreSQL original ↗

23 Nov 2009

SQL Server: are the recursive CTE’s really set-based?original ↗

18 Nov 2009

Selecting most relevant row original ↗

17 Nov 2009

Inverting date ranges: MySQL original ↗

12 Nov 2009

SQL Server: clustered index and ordering original ↗

11 Nov 2009

MySQL: average of sums using indexes original ↗

10 Nov 2009

Inverting date ranges original ↗

9 Nov 2009

MySQL ORDER BY / LIMIT performance: late row lookups original ↗

23 Oct 2009

Generating row placeholders: SQL Server original ↗

21 Oct 2009

What is entity-relationship model?original ↗

18 Oct 2009

Constraints and the optimizer in SQL Server: FOREIGN KEY original ↗

15 Oct 2009

Constraints and the optimizer in SQL Server: PRIMARY KEY and UNIQUE original ↗

14 Oct 2009

Running root mean square: SQL Server original ↗

13 Oct 2009

Minimum and maximum on bit fields: SQL Server original ↗

12 Oct 2009

Oracle: nested SUM original ↗

8 Oct 2009

IN list vs. range condition: MySQL original ↗

7 Oct 2009