Add Write A Query Result To File as a postgres til

README.md

@@ -10,7 +10,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 For a steady stream of TILs from a variety of rocketeers, checkout
 [til.hashrocket.com](https://til.hashrocket.com/).
 
-_527 TILs and counting..._
+_528 TILs and counting..._
 
 ---
 
@@ -329,6 +329,7 @@ _527 TILs and counting..._
 - [Using Intervals To Offset Time](postgres/using-intervals-to-offset-time.md)
 - [Who Is The Current User](postgres/who-is-the-current-user.md)
 - [Word Count for a Column](postgres/word-count-for-a-column.md)
+- [Write A Query Result To File](postgres/write-a-query-result-to-file.md)
 
 ### Rails
 

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

@@ -0,0 +1,29 @@
+# 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.