[Sqlalchemy-tickets] Issue #3418: preserve CTE from a SELECT when doing INSERT...SELECT (zzzeek/sqlalchemy)

[Mike B. <iss...@bi...>]

New issue 3418: preserve CTE from a SELECT when doing INSERT...SELECT
https://bitbucket.org/zzzeek/sqlalchemy/issue/3418/preserve-cte-from-a-select-when-doing

Mike Bayer:

related to #2551 but of lesser scope, if the select() passed to insert.from_select() has a cte() inside of it, we should render that inline:


```
#!sql

    INSERT INTO data (id, data) WITH anon_1 AS
    (SELECT data2.id AS id, data2.data AS data
    FROM data2
    WHERE data2.data = 1)
     SELECT data2.id, data2.data
    FROM data2, anon_1
    WHERE data2.data = anon_1.data

```

PG supports the WITH both on top and under the INSERT, and they have different semantics:
http://www.postgresql.org/docs/9.4/interactive/sql-insert.html  "It is possible for the query (SELECT statement) to also contain a WITH clause. In such a case both sets of with_query can be referenced within the query, but the second one takes precedence since it is more closely nested.".