From 4ad80040c3e75c23c916b08dc2d53380452971c6 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Wed, 13 Mar 2024 21:29:04 -0700
Subject: [PATCH] SQLite timestamps with floating point seconds

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 sqlite/floating-point-seconds.md | 39 ++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 sqlite/floating-point-seconds.md

diff --git a/sqlite/floating-point-seconds.md b/sqlite/floating-point-seconds.md
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+# SQLite timestamps with floating point seconds
+
+Today I learned about this:
+
+```sql
+select strftime('%Y-%m-%dT%H:%M:%f')
+```
+Which outputs:
+```
+2024-03-14T04:23:25.087Z
+```
+Note the seconds component which reads `25.087` - that's what you get from the `%f` format string.
+
+This is useful because it provides a string which captures timestamp information at the millisecond level but can still be sorted alphabetically to sort by date.
+
+I spotted this in [the SQL schema](https://github.com/maragudk/goqite/blob/main/schema.sql) for [goqite](https://github.com/maragudk/goqite) by Markus Wüstenberg, who uses it for recording `created` and `updated` timestamps:
+```sql
+create table goqite (
+  id text primary key default ('m_' || lower(hex(randomblob(16)))),
+  created text not null default (strftime('%Y-%m-%dT%H:%M:%fZ')),
+  updated text not null default (strftime('%Y-%m-%dT%H:%M:%fZ')),
+  queue text not null,
+  body blob not null,
+  timeout text not null default (strftime('%Y-%m-%dT%H:%M:%fZ')),
+  received integer not null default 0
+) strict;
+
+create trigger goqite_updated_timestamp after update on goqite begin
+  update goqite set updated = strftime('%Y-%m-%dT%H:%M:%fZ') where id = old.id;
+end;
+```
+Another neat trick in that schema:
+```sql
+select lower(hex(randomblob(16)))
+```
+Which returns random strings like this one, suitable for use as IDs:
+```
+b4496695399120dfa999bff9981467b1
+```