ch 15: update query draft

Author: razetime

15-tables-files.md

@@ -62,9 +62,16 @@ The same goes for `_`.
 +`a`b!(,1;,3)
 ```
 
+<!--
 Updates to a table have to be done with indexing. An SQL group by query had to
 be done with `=`, which returns a dictionary that has to be reconstituted into
-a list of lists. 
+a table.
+
+```
+ t:+`a`b!(!10;10?10)
+ ,/t@=2!t@`a
+```
+-->
 
 ## File Model
 ngn/k's file I/O is based on the UNIX model of file management. It is best to