Fix: execute() should return rows affected by operation if lastrowid is not set.

[gnat]

Patch closes the following issues:

• How to check if .execute(.) went through ? #142
• Support returning the rowcount for a given query? #61

Old behavior: Calls to execute() return lastrowid. For some operations this has no benefit.

New behavior: Calls to execute() where lastrowid has no benefit will now return rows affected by the operation. (Example: DELETE. So we can now see if a DELETE was successful, and how many rows were deleted). Calls which set a lastrowid value, will still retain the old behavior.

The library encode/databases depends on, aiomysql, returns rows affected, the desired behaviour this patch implements. See: https://github.com/aio-libs/aiomysql/blob/master/aiomysql/cursors.py#L244

[gnat]

@tomchristie Possible to get this merged?

[gvbgduh]

Oh, nice! That makes sense. That would also apply for the upcoming aiopg backend.
For asyncpg it'll be a bit diff tho, as it returns exactly what postgres returns back, which is of the following form:

for insert

INSERT oid count

for update:

UPDATE count

for delete:

DELETE count

As a plain string, so simple parsing should. Would be very nice to add it to this PR as well, but I can push it a bit later with a different issue to not forget to update aiopg when it's merged.

[gnat]

@gvbgduh That sounds like a great plan. In the mean time, is there anything holding up getting this merged?

[gvbgduh]

@gnat sorry for a delay, merging it now

[gnat]

Amazing, thank you @gvbgduh !