Updated README

Author: README-bot

README.md

@@ -4,7 +4,7 @@ My Today I Learned snippets. Inspired by [jbranchaud/til](https://github.com/jbr
 
 Search these TILs at https://til.simonwillison.net/
 
-<!-- count starts -->192<!-- count ends --> TILs so far. <a href="https://til.simonwillison.net/til/feed.atom">Atom feed here</a>.
+<!-- count starts -->193<!-- count ends --> TILs so far. <a href="https://til.simonwillison.net/til/feed.atom">Atom feed here</a>.
 
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 ## github-actions
@@ -320,6 +320,7 @@ Search these TILs at https://til.simonwillison.net/
 
 * [Finding duplicate records by matching name and nearby distance](https://github.com/simonw/til/blob/main/sql/finding-dupes-by-name-and-distance.md) - 2021-05-19
 * [Building a Markdown summary of Django group permissions](https://github.com/simonw/til/blob/main/sql/django-group-permissions-markdown.md) - 2021-06-03
+* [Cumulative total over time in SQL](https://github.com/simonw/til/blob/main/sql/cumulative-total-over-time.md) - 2021-09-13
 
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