doc/md: custom ordering example

doc/md/paging.md

@@ -48,4 +48,22 @@ users, err := client.Pet.Query().
 	Order(ent.Asc(pet.FieldName)).
 	QueryOwner().
 	All(ctx)
+```
+
+## Custom Ordering
+
+Custom ordering functions can be useful if you want to write your own storage-specific logic.
+
+The following shows how to order pets by their name, and their owners' name in ascending order.
+
+```go
+names, err := client.Pet.Query().
+	Order(func(s *sql.Selector) {
+		// Join with user table for ordering by owner-name and pet-name.
+		t := sql.Table(user.Table)
+		s.Join(t).On(s.C(pet.OwnerColumn), t.C(user.FieldID))
+		s.OrderBy(t.C(user.FieldName), s.C(pet.FieldName))
+	}).
+	Select(pet.FieldName).
+	Strings(ctx)
 ```

doc/md/predicates.md

@@ -102,26 +102,14 @@ users := client.User.
 		s.Where(sqljson.HasKey(user.FieldURL, sqljson.Path("Scheme")))
 	})).
 	AllX(ctx)
-```
 
-
-Also It can be used in subquery case, for example:
-
-```sql
-SELECT DISTINCT `todos`.`id`, `todos`.`text`, `todos`.`done` 
-    FROM `todos` WHERE `todos`.`user_id` IN (
-        SELECT `id` FROM `users` WHERE `users`.`id` IN (?, ?)
-    )
-```
-
-```go
 todos := client.Todo.Query().
     Where(func(s *sql.Selector) {
         t := sql.Table(user.Table)
         s.Where(
             sql.In(
                 s.C(todo.FieldUserID),
-                sql.Select(t.C(user.FieldID)).From(t).Where(sql.In(t.C(user.FieldID), ids...)),
+                sql.Select(t.C(user.FieldID)).From(t).Where(sql.In(t.C(user.FieldName), names...)),
             ),
         )
     }).