unique

问题 Is there a way to make an existing txt field unique (do not accept duplicated values)? Field: post_title Type: text Collation: utf8_unicode_ci Null: Sim Default: NULL What gonna happens if someone tries to insert a post with an existing title? Could that affect some functionality of my site? Structure CREATE TABLE IF NOT EXISTS `hotaru_posts` ( `post_id` int(20) NOT NULL AUTO_INCREMENT, `post_archived` enum('Y','N') COLLATE utf8_unicode_ci NOT NULL DEFAULT 'N', `post_updatedts` timestamp NOT

问题 I have the following XML: <MyFruits> <Apple>A</Apple> <Apple>19</Apple> <Mango>12</Mango> <Apple>19</Apple> <Orange>A</Orange> <Orange>A</Orange> <Orange>A</Orange> <Apple>B</Apple> <Apple>19</Apple> <Mango>12</Mango> <Apple>19</Apple> <Orange>10</Orange> <Apple>19</Apple> <Orange>10</Orange> <Apple>C</Apple> <Apple>19</Apple> <Mango>12</Mango> <Apple>19</Apple> <Orange>10</Orange> <Apple>19</Apple> <Orange>10</Orange> </MyFruits> I want to get only unique fruits among them (Apple,Mango and

问题 Have a program where the user inputs 10 int values into the array. Lastly I need to pull out the distinct values and display them. Added my second for loop which would determine if the the value is distinct (i.e. meaning if the number appears multiple times it is only displayed once). For instance, let say I pass in the numbers: 1, 2, 3, 2, 1, 6, 3, 4, 5, 2 the distinct array should only contain numbers {1, 2, 3, 6, 4, 5} import java.util.Scanner; import java.io.*; public class ArrayDistinct

问题 It looks like mongoose supported field level uniqueness constraints in earlier versions as follows (seen in 2.7.x here): var SomeSchema = new Schema ({ field: {index: {unique: true}} // field level }) I can't find any reference to it in the 4.4.x docs. Is the preferred way to do this on the schema level now, like so (seen in 4.4.x here): SomeSchema.index({field: 1}, {unique: true}) // schema level 回答1: Yes, unique indexes are still supported in Mongoose; see here and here in the current docs.

问题 I have a DT with three columns, and the two first ones have various values grouped by Group. ID ID_2 Group 23201600101793 2016052016051062331 A 23201600101793 2016062016061017838 A 23201600101794 2016052016051062331 A 23201600101794 2016052016051062402 A 23201600103090 2016052016051062325 A 23201600103090 2016052016051062408 A 23201600803366 2016052016051062325 A 23201600803366 2016052016051062408 A I need to find a unique combination of both columns, withtout repeated values in any column.

问题 I need to get time based unique id which would only consist of numbers, i was thinking to simply use something like this: str_replace(".", "", microtime(true)) I would use this id for many things, for example comments posting, and i'm expecting quite high traffic so i would like to know how high are the chances of collision with microtime function? And perhaps there is a better way to get numerical unique id? Just remember that it has to based on time so sorting could be done. 回答1: If you

问题 So I'm downloading a JSON dataset from a webservice and storing them in core data after parsing. One of the entities has unique constraint set, as I don't want redundunct data in the entity. This causes "NSConstraintConflict" exception to be thrown whenever an entry value is already existed in the Core Data. Right now, I'm not handling this exception and let it be thrown. Is it a proper way to handle this situation or is there a better way? 来源： https://stackoverflow.com/questions/46076841

问题 Ok guys, i need to implement this for a photo contest ... i have a main set of N pictures, and i need to generate the permutations of size 2 of those pics without having repetitions, for instance: foo.png VS bar.png is equal to bar.png VS foo.png Another thing, i can not pre generate al permutations each time, so i need a function that, given the previous permutation, will return me the next one (or NULL if the possible unique permutations are over). I solved this problem with the following

问题 I'm trying to loop through a multidimensional array and retreive unique values(case insensitive), can anyone help me? $shop = array( array( 'Title' => "General enquiries", 'Phone' => 02085237289, ), array( 'Title' => "general enquiries", 'email' => 'something@gmail.com', ), array( 'Title' => "not enquiries", 'Phone' => 02039303039, ), array( 'Title' => "Not enquiries", 'email' => 'blah@gmail.com', ) ); This what i'm trying to create: General Enquiries 02085237289 something@gmail.com Not

问题 I have a strange problem. To illustrate: a <- c(3.099331946117620972814, 3.099331946117621860992) > unique(a) [1] 3.099331946117620972814 3.099331946117621860992 > table(a) a 3.09933194611762 2 So unique() correctly recognises that the numbers are different after the 15th digit. table() however does not consider them different. This may be expected behaviour but it is causing an error in some of my code as I need them both to agree: times <- sort(unique(times)) k <- as.numeric(table(times))