feat: update readme with info how to drop trigger and trigger funcitons

migrations/README.md

@@ -31,3 +31,40 @@ migrate -database ${POSTGRESQL_URL} -path migrations up
 ```bash
 migrate -database ${POSTGRESQL_URL} -path migrations down
 ```
+
+# How to manually change/remove/list triggers and trigger functions
+
+To list all trigger function, use this query:
+
+```sql
+SELECT n.nspname as schema,
+       p.proname as function_name
+FROM pg_proc p
+JOIN pg_namespace n ON p.pronamespace = n.oid
+WHERE p.prorettype = 'pg_catalog.trigger'::pg_catalog.regtype;
+```
+
+To list all triggers, use this query:
+
+```sql
+SELECT event_object_schema as table_schema,
+       event_object_table as table_name,
+       trigger_name,
+       action_timing as trigger_time,
+       event_manipulation as event,
+       action_statement as definition
+FROM information_schema.triggers
+ORDER BY table_schema, table_name, trigger_name;
+```
+
+To drop trigger (if any), use this mutation:
+
+```sql
+DROP TRIGGER IF EXISTS your_trigger_name ON your_table_name;
+```
+
+To drop trigger function, use this mutation:
+
+```sql
+DROP FUNCTION IF EXISTS your_schema_name.your_trigger_function_name();
+```