duplicate-removal

I have a table item that contains items like name ------ alpha alpha beta charlie charlie In this case how would I delete duplicate rows but one record should remain. The above table does not have any primary key. Try this DELETE FROM item WHERE GREATEST(0,@num := IF(NAME = @NAME, @num + 1, 0),LEAST(0, LENGTH(@NAME := NAME)))>0 Recreate that table: RENAME TABLE `testTable` TO `testTable2`; CREATE TABLE `testTable` SELECT DISTINCT `name` FROM `testTable2`; OR Add UNIQUE INDEX on your field. ALTER IGNORE TABLE `tableName` ADD UNIQUE INDEX (`name`) 来源： https://stackoverflow.com/questions/14357888

I'm looking for a way to remove duplicate entries from a Python list but with a twist; The final list has to be case sensitive with a preference of uppercase words. For example, between cup and Cup I only need to keep Cup and not cup . Unlike other common solutions which suggest using lower() first, I'd prefer to maintain the string's case here and in particular I'd prefer keeping the one with the uppercase letter over the one which is lowercase.. Again, I am trying to turn this list: [Hello, hello, world, world, poland, Poland] into this: [Hello, world, Poland] How should I do that? Thanks in

What is a clever way to remove rows from a CSV file in ruby where a particular value exists in a particular row? Here's an example of a file: 350 lbs., Outrigger Footprint, 61" x 53", Weight, 767 lbs., 300-2080 350 lbs., Outrigger Footprint, 61" x 53", Weight, 817 lbs., 300-2580 350 lbs., Outrigger Footprint, 61" x 53", Weight, 817 lbs., 300-2580 350 lbs., Outrigger Footprint, 69" x 61", Weight, 867 lbs., 300-3080 350 lbs., Outrigger Footprint, 69" x 61", Weight, 867 lbs., 300-3080 Ideally, I'd want a new file created with only this: 350 lbs., Outrigger Footprint, 61" x 53", Weight, 767 lbs.,

Having approximately 600GB of photos collected over 13 years - now stored on freebsd zfs/server. Photos comes from family computers, from several partial backups to different external USB HDDs, reconstructed images from disk disasters, from different photo manipulation softwares (iPhoto, Picassa, HP and many others :( ) in several deep subdirectories - shortly = TERRIBLE MESS with many duplicates. So in the first i done: searched the the tree for the same size files (fast) and make md5 checksum for those. collected duplicated images (same size + same md5 = duplicate) This helped a lot, but

I am working on a project where I am processing a lot of tweets; the goal is to remove duplicates as I process them. I have the tweet IDs, which come in as strings of the format "166471306949304320" I have been using a HashSet<String> for this, which works fine for a while. But by the time I get to around 10 million items I am drastically bogged down and eventually get a GC error, presumably from the rehashing. I tried defining a better size/load with tweetids = new HashSet<String>(220000,0.80F); and that lets it get a little farther, but is still excruciatingly slow (by around 10 million it

I have a file (size = ~1.9 GB) which contains ~220,000,000 (~220 million) words / strings. They have duplication, almost 1 duplicate word every 100 words. In my second program, I want to read the file. I am successful to read the file by lines using BufferedReader. Now to remove duplicates, we can use Set (and it's implementations), but Set has problems, as described following in 3 different scenarios: With default JVM size, Set can contain up to 0.7-0.8 million words, and then OutOfMemoryError. With 512M JVM size, Set can contain up to 5-6 million words, and then OOM error. With 1024M JVM