Merge pull request #7

Add the first page for the `JOIN` series

README.md

@@ -8,7 +8,7 @@
 [![SQL Server](https://img.shields.io/badge/SQL%20Server-2022-teal.svg)](https://www.microsoft.com/en-gb/sql-server/sql-server-downloads)
 [![PostgreSQL](https://img.shields.io/badge/PostgreSQL-15.4-teal.svg)](https://www.postgresql.org/download/)
 [![SQLite](https://img.shields.io/badge/SQLite-3.43-teal.svg)](https://www.sqlite.org/index.html)
-[![DuckDB](https://img.shields.io/badge/DuckDB-0.10-teal.svg)](https://duckdb.org/)
+[![DuckDB](https://img.shields.io/badge/DuckDB-0.9-teal.svg)](https://duckdb.org/)
 
 </div>
 

docs/everything-about-joins/everything-about-joins.md

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+# Everything about joins
+
+## About this course
+
+> [!SUCCESS]
+>
+> Everything you need to know about SQL joins 🎉
+
+## The tools/data in this course
+
+This course will primarily use [DuckDB](https://duckdb.org/) as the database engine, but will also mention [SQLite](https://www.sqlite.org/), [PostgreSQL](https://www.postgresql.org/), [SQL Server](https://learn.microsoft.com/en-us/sql/sql-server/?view=sql-server-ver16), and [Snowflake](https://docs.snowflake.com/).
+
+The data will be made up for the examples.
+
+## Outline
+
+1. **Syntax**
+   1. SQL-92 rant (ANSI-SQL join syntax)
+   2. Join fundamentals: `INNER`, `LEFT` (`RIGHT`), `FULL`, `CROSS`
+   3. More fundamentals: `USING`, `NATURAL`
+   4. [The "timestamp" join: `ASOF`](syntax/timestamp-joins.md)
+2. **Under the hood**
+   1. ...

docs/everything-about-joins/syntax/filtering-joins.md

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+# The "filtering" joins (`SEMI`, `ANTI`)
+
+> [!SUCCESS]
+>
+> The `SEMI` and `ANTI` joins are slightly different from typical joins because they're used to _filter_ the rows from the left table based on the presence or absence of a match in the right table.