Updating row selected by cursor irish traveller dating site

23-Apr-2020 22:52

The started seeing how they are bad, and trying to wrap my head around set based. Sorry, this is an anti-pattern called cargo cult programming: not knowing WHY cursors are considered bad, you implement something even worse!Imagine you couldn't concatenate strings in a set based query (using COALESCE in SQL Server, for example), then the cursor would be the method of choice.In fact, using a table variable with read only, forward only cursors is a fine combination: one can iterate over all records in a fast manner, without worrying about locks.Like this guy does (just look at the activator procedure): com/b/sql_service_broker/archive/2008/07/25/…FAST_FORWARD will create an optimised forward-only, read-only cursor.Read about the available options before ruling all cursors as evil.Each one has different performance characteristics and associated overhead.Make sure you use the correct cursor type for your operation. One argument for using a cursor is when you need to process and update individual rows, especially for a dataset that doesn't have a good unique key.

updating row selected by cursor-17updating row selected by cursor-80updating row selected by cursor-87updating row selected by cursor-36

I think cursors are still a bad choice unless you understand enough about them to justify their use in limited circumstances. The cursor block is so ugly that it's difficult to use in a clear and effective way.

This way i dont lock anything and use alot less memory and its safe, i will not lose anything with a memory corruption or something like that. This is a simple example: DECLARE @TAB TABLE(ID INT IDENTITY, COLUMN1 VARCHAR(10), COLUMN2 VARCHAR(10)) DECLARE @COUNT INT, @MAX INT, @CONCAT VARCHAR(MAX), @COLUMN1 VARCHAR(10), @COLUMN2 VARCHAR(10) SET @COUNT = 1 INSERT INTO @TAB VALUES('TE1S', 'TE21') INSERT INTO @TAB VALUES('TE1S', 'TE22') INSERT INTO @TAB VALUES('TE1S', 'TE23') INSERT INTO @TAB VALUES('TE1S', 'TE24') INSERT INTO @TAB VALUES('TE1S', 'TE25') SELECT @MAX = @@IDENTITY WHILE @COUNT I like that method.

I just recently started needing to use SQL this much, and came across using a cursor.

But, when you open a cursor, you are basically loading those rows into memory and locking them, creating potential blocks.

Then, as you cycle through the cursor, you are making changes to other tables and still keeping all of the memory and locks of the cursor open.

I think cursors are still a bad choice unless you understand enough about them to justify their use in limited circumstances. The cursor block is so ugly that it's difficult to use in a clear and effective way.This way i dont lock anything and use alot less memory and its safe, i will not lose anything with a memory corruption or something like that. This is a simple example: DECLARE @TAB TABLE(ID INT IDENTITY, COLUMN1 VARCHAR(10), COLUMN2 VARCHAR(10)) DECLARE @COUNT INT, @MAX INT, @CONCAT VARCHAR(MAX), @COLUMN1 VARCHAR(10), @COLUMN2 VARCHAR(10) SET @COUNT = 1 INSERT INTO @TAB VALUES('TE1S', 'TE21') INSERT INTO @TAB VALUES('TE1S', 'TE22') INSERT INTO @TAB VALUES('TE1S', 'TE23') INSERT INTO @TAB VALUES('TE1S', 'TE24') INSERT INTO @TAB VALUES('TE1S', 'TE25') SELECT @MAX = @@IDENTITY WHILE @COUNT I like that method.I just recently started needing to use SQL this much, and came across using a cursor.But, when you open a cursor, you are basically loading those rows into memory and locking them, creating potential blocks.Then, as you cycle through the cursor, you are making changes to other tables and still keeping all of the memory and locks of the cursor open.The above comments about SQL being a set-based environment are all true.