Add Experiment With SQLite Queries In Memory as a Python TIL

python/experiment-with-sqlite-queries-in-memory.md

@@ -0,0 +1,44 @@
+# Experiment With SQLite Queries In Memory
+
+Instead of connecting
+[`sqlite3`](https://docs.python.org/3/library/sqlite3.html) to a real file
+(database) like so:
+
+```python
+db_file: Path = data_dir / "sessions.db"
+conn: Connection = sqlite3.connect(db_file)
+```
+
+I can point it to `":memory:"`:
+
+```python
+conn: Connection = sqlite3.connect(":memory:")
+```
+
+One way this can be useful is when experimenting with some DDL (schema-modifying
+SQL statements), e.g. creating a table, adding a column, and so forth.
+
+```python
+>>> import sqlite3
+>>> conn = sqlite3.connect(":memory:")
+>>> conn.execute("""
+... create table projects (
+...     id integer primary key,
+...     name text not null unique,
+...     created_at text not null default (datetime('now')),
+...     updated_at text not null default (datetime('now'))
+... );
+... """)
+<sqlite3.Cursor object at 0x105d6e2c0>
+>>> conn.execute("insert into projects (name) values ('TIL'), ('py-vmt'), ('Pool League Pro');")
+<sqlite3.Cursor object at 0x105d6e340>
+>>> result = conn.execute("select * from projects;")
+>>> rows = result.fetchall()
+>>> rows
+[(1, 'TIL', '2026-08-01 23:59:56', '2026-08-01 23:59:56'), (2, 'py-vmt', '2026-08-01 23:59:56', '2026-08-01 23:59:56'), (3, 'Pool League Pro', '2026-08-01 23:59:56', '2026-08-01 23:59:56')]
+```
+
+This does not create any sort of on-disk version of the database. Two separate
+connections created this way will be independent in-memory database instances.
+This is technically more of [a SQLite feature](https://sqlite.org/inmemorydb.html) than a Python one, but it was in a
+Python context that I found this most useful.