When to use a cursor

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When to use a cursor

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SQLZ SSChampion Points: 12872 More actions · Answer 1

Jeff Moden (4/1/2008)

Ah ha! Finally! A challenge! If you would, post the resulting table creation script so I can duplicate what you have... the race is on! :w00t:

Sent you an email Jeff. This should be interesting. 🙂

Karl
source control for SQL Server

matt stockham SSCrazy Eights Points: 9942 More actions · Answer 2

cjudge (4/1/2008)What you guys have to remember - and the above quote is perfect - is that the only reason you are managing the database is so that someone can use the data. In no way do I mean this to imply that the administrative/managerial tasks are not important. However, administration is "set-based" while using data is often record-based. There are countless examples:
1. A piece of software must gather all new submissions (a record set) and step through the set (a cursor) presenting some data from the record (e.g. a suspect's photograph) to a human reviewer for review.
2. A piece of software must find all records sharing some ID ( a record set) and then step through those records (a cursor) performing the instructions encoded in each record (e.g. probing remote sensors for current readings) and waiting for a return value before proceeding.
etc.
These all generalize to the following: A piece of software must perform an external process on each record in a record set.

This is very true ... except the stepping process should be done client side using the results of a set-based query.

John Rowan SSC Guru Points: 56440 More actions · Answer 3

Exactly, Matt's hit the nail on the head. The data should be retrieved from the database as a set based query. The application can perform any looping or cursoring operations against a detached recordset where it is not impacting server resources. What concerns me is that the data is retrieved efficiently.

John Rowan

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Forum Etiquette: How to post data/code on a forum to get the best help[/url] - by Jeff Moden

Jeff Moden SSC Guru Points: 1004366 More actions · Answer 4

matt stockham (4/1/2008)
This is very true ... except the stepping process should be done client side using the results of a set-based query.

Absolutely spot on!

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Jeff Moden SSC Guru Points: 1004366 More actions · Answer 5

SQLZ (4/1/2008)

Jeff Moden (4/1/2008)
Ah ha! Finally! A challenge! If you would, post the resulting table creation script so I can duplicate what you have... the race is on! :w00t:
Sent you an email Jeff. This should be interesting. 🙂

Outstanding... thanks Karl!

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)