tables doc

doc/user-guide/tables-columns.md

@@ -68,12 +68,25 @@ Pass `--schema/-s` to get tables in a different schema:
 
 +++
 
-JupySQL also supports variable expansion of arguments in the form of `{{variable}}`. Let's see an example:
+JupySQL also supports variable expansion of arguments in the form of `{{variable}}`. Let's see an example of parametrizing `schema`:
+
+```{code-cell} ipython3
+from sqlalchemy import create_engine
+from sql.connection import SQLAlchemyConnection
+
+conn = SQLAlchemyConnection(engine=create_engine("sqlite:///my.db"))
+conn.execute("CREATE TABLE numbers (n FLOAT)")
+```
 
 ```{code-cell} ipython3
 schema = "schema"
 ```
 
+```{code-cell} ipython3
+%%sql
+ATTACH DATABASE 'my.db' AS {{schema}}
+```
+
 ```{code-cell} ipython3
 %sqlcmd tables --schema {{schema}}
 ```