docs: clarify that only INSERT and UPDATE triggers can mod. NEW

The point is that DELETE triggers cannot modify any values.

Reported-by: Eugen Konkov
Discussion: https://postgr.es/m/919823407.20191029175436@yandex.ru

Backpatch-through: 9.4

diff --git a/doc/src/sgml/trigger.sgml b/doc/src/sgml/trigger.sgml
index 4d3fc8e0f89cfa5856f6c5170dbaa947f8335a2e..647d96ef1d83030797e8a5e2b52a55f68fa1e128 100644 (file)
--- a/doc/src/sgml/trigger.sgml
+++ b/doc/src/sgml/trigger.sgml
@@ -204,7 +204,7 @@
     used to signal that the trigger performed the necessary data
     modifications in the view.  This will cause the count of the number
     of rows affected by the command to be incremented. For
-    <command>INSERT</> and <command>UPDATE</> operations, the trigger
+    <command>INSERT</> and <command>UPDATE</> operations only, the trigger
     may modify the <varname>NEW</> row before returning it.  This will
     change the data returned by
     <command>INSERT RETURNING</> or <command>UPDATE RETURNING</>,