Add Edit Existing Functions as a postgres til.

README.md

@@ -59,6 +59,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Configure The Timezone](postgres/configure-the-timezone.md)
 - [Count Records By Type](postgres/count-records-by-type.md)
 - [Default Schema](postgres/default-schema.md)
+- [Edit Existing Functions](postgres/edit-existing-functions.md)
 - [Extracting Nested JSON Data](postgres/extracting-nested-json-data.md)
 - [Fizzbuzz With Common Table Expressions](postgres/fizzbuzz-with-common-table-expressions.md)
 - [Generate Series Of Numbers](postgres/generate-series-of-numbers.md)

postgres/edit-existing-functions.md

@@ -0,0 +1,21 @@
+# Edit Existing Functions
+
+In the `psql` console, use `\ef` with the name of a function to fetch and
+open the definition of the function. The function will be opened in your
+system `$EDITOR` in the form of the `create or replace function` query.
+
+Executing
+
+```sql
+> \ef now
+```
+
+will open the following in your default editor
+
+```sql
+CREATE OR REPLACE FUNCTION pg_catalog.now()¬
+ RETURNS timestamp with time zone¬
+ LANGUAGE internal¬
+ STABLE STRICT¬
+AS $function$now$function$¬
+```