Re: proposal - assign result of query to psql variable

2012/10/16 Shigeru HANADA <shigeru(dot)hanada(at)gmail(dot)com>:
> Hi Pavel,
>
> On Tue, Oct 16, 2012 at 6:59 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
> wrote:
>> here is updated patch, I moved lot of code from lexer to command.com,
>> and now more \gset doesn't disable other backslash commands on same
>> line.
>
> * lexer changes
> IIUC, new function psql_scan_varlist_varname scans input and returns a
> variable name or a comma at each call, and command.c handles the error
> such as invalid # of variables. This new design seems better than old one.
>
> However, IMHO the name psql_scan_varlist_varname sounds redundant and
> unintuitive. I'd prefer psql_scan_slash_varlist, because it indicates
> that that function is expected to be used for arguments of backslash
> commands, like psql_scan_slash_command and psql_scan_slash_option.
> Thoughts?
>
> * multiple meta command
> Now both of the command sequences
>
> $ SELECT 1, 2 \gset var1, var2 \g foo.txt
> $ SELECT 1, 2 \g foo.txt \gset var1, var2
>
> set var1 and v2 to "1" and "2" respectively, and also write the result
> into foo.txt. This would be what users expected.
>
> * Duplication of variables
> I found an issue we have not discussed. Currently \gset accepts same
> variable names in the list, and stores last SELECT item in duplicated
> variables. For instance,
>
> $ SELECT 1, 2 \gset var, var
>
> stores "2" into var. I think this behavior is acceptable, but it might
> be worth mentioning in document.
>
> * extra fixes
> I fixed some minor issues below. Please see attached v10 patch for details.
>
> * remove unused macro OT_VARLIST
> * remove unnecessary #include directive for common.h
> * fill comment within 80 columns
> * indent short variable name with tab
> * add regression test case for combination of \g and \gset
>
> * bug on FETCH_COUNT = 1
> When FETCH_COUNT is set to 1, and the number of rows returned is 1 too,
> \gset shows extra "(1 row)". This would be a bug in
> ExecQueryUsingCursor. Please see the last test case in regression test
> psql_cmd.

I fixed this bug

Regards

Pavel

>
> I'll mark this patch as "waiting author".
>
> Regards,
> --
> Shigeru HANADA