On 10/01/2014 07:28 PM, Thomas Munro wrote:
Hi
SQL:2003 introduced the function NEXT VALUE FOR <sequence>. Google
tells me that at least DB2, SQL Server and a few niche databases
understand it so far. As far as I can tell there is no standardised
equivalent of currval and setval (but I only have access to second
hand information about the standard, like articles and the manuals of
other products).
Here is a starter patch to add it. To avoid a shift/reduce conflict,
I had to reclassify the keyword NEXT. I admit that I don't fully
understand the consequences of that change! Please let me know if you
think this could fly.
Looks correct. Of course, it's annoying to have to reserve the NEXT
keyword (as a type_func_name_keyword, not fully reserved).
One way to avoid that is to collapse NEXT VALUE FOR into a single token
in parser.c. We do that for a few other word pairs: NULLS FIRST, NULLS
LAST, WITH TIME and WITH ORDINALITY. In this case you'd need to
look-ahead three tokens, not two, but I guess that'd be doable.
- Heikki
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