Add Write A Query Result To File as a postgres til

postgres/write-a-query-result-to-file.md

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+# Write A Query Result To File
+
+Generally when writing a query in `psql` a statement will be terminated with
+a semicolon. An alternative approach is to end it with a `\g` instead. This
+will also send the query to the Postgres server for execution.
+
+```sql
+select 1 \g
+```
+
+If a filename is included after the `\g`, then the result of the query will
+be written to that file instead of output to the `psql` session.
+
+```sql
+> select 1, 2, 3 \g query_result.txt
+```
+
+If we `cat` that file, we can see the query result.
+
+```sql
+Time: 4.293 ms
+> \! cat query_result.txt
+ ?column? | ?column? | ?column?
+----------+----------+----------
+        1 |        2 |        3
+(1 row)
+```
+
+See `man psql` for more details.