Talk:Cursor (databases)
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I presume that there must be some pros with cursors as well? Senappp 21:50, 1 January 2006 (UTC)
- Yeah, there are. This article is in pretty poor shape, and I mean to add to it. Time is the limiter, as usual. -- Mikeblas 21:59, 1 January 2006 (UTC)
- I'm finally getting 'round to this, so please be patient in the interim. -- Mikeblas 00:35, 7 June 2006 (UTC)
- Great! -- Patrickdepinguin 20:37, 9 June 2006 (UTC)
- I'm finally getting 'round to this, so please be patient in the interim. -- Mikeblas 00:35, 7 June 2006 (UTC)
- Of course there are, or they wouldn't have been invented in the first place. There are (limited) situations where they make the difference between something being possible or impossible. Which is a pretty compelling advantage in my book. I've already begun improving the article, but will attempt to address this and include a real-world example or two. DigitalEnthusiast 00:54, 15 December 2006 (UTC)
- I believe that the "disadvantages" section is partly wrong and partly very imprecise. First, cursors are the only way to transfer data from a relational DBMS to a procedural application (with the exception being a SELECT INTO statement). Next, a FETCH does not imply a network round-trip at all - the DBMS client can use block fetch. Also, what are those "restrictions on SELECT statements" and what is the complex syntax? Examples would be important! After all, declaring a cursor is just prefixing a SELECT statement with DECLARE cursor-name CURSOR FOR statement. Finally, I believe that system-specific things like SQL Server's implementation based on temp tables should go into a separate (sub)section. --Stolze 13:46, 20 December 2006 (UTC)
- I'm actually not aware of any restrictions on the SELECT statement; however cursors are not the only way to get data from the db engine to the client app - the DataReader class in .net parses a TDS or Oracle network stream directly as it's sent up. As for the "complex syntax," I think that's showing up because most people who've used SQL are used to set-based operations, and not procedural coding. DigitalEnthusiast 20:58, 20 December 2006 (UTC)
- I believe that the "disadvantages" section is partly wrong and partly very imprecise. First, cursors are the only way to transfer data from a relational DBMS to a procedural application (with the exception being a SELECT INTO statement). Next, a FETCH does not imply a network round-trip at all - the DBMS client can use block fetch. Also, what are those "restrictions on SELECT statements" and what is the complex syntax? Examples would be important! After all, declaring a cursor is just prefixing a SELECT statement with DECLARE cursor-name CURSOR FOR statement. Finally, I believe that system-specific things like SQL Server's implementation based on temp tables should go into a separate (sub)section. --Stolze 13:46, 20 December 2006 (UTC)
A description of the differences between the five types of cursors would be helpful. --Sapphire Wyvern 03:13, 6 September 2006 (UTC)
[edit] Multi-row fetch
The most current SQL standard SQL:2003 does not know the concept of multi-row fetch. Subclause 14.3, "<fetch statement>" has this BNF:
<fetch statement> ::=
FETCH [ [ <fetch orientation> ] FROM ] <cursor name> INTO <fetch target list>
<fetch orientation> ::=
NEXT
| PRIOR
| FIRST
| LAST
| { ABSOLUTE | RELATIVE } <simple value specification>
<fetch target list> ::=
<target specification> [ { <comma> <target specification> }... ]
No multi-row stuff here. So I removed this again. --Stolze 15:23, 26 March 2007 (UTC)
[edit] Cursors make you curse
Probably not worthy of trivia, but I had a boss who said this once, and he wasn't very creative, leading me to think someone told him ... DigitalEnthusiast 19:55, 21 December 2006 (UTC)
