no-duplicates | 易学教程

JAVA, SQL, insert into no-duplicates

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问题 I am trying to insert into a table without duplicates. I am using SQL derbyclient in Java. The code is not working (error with 'where not exists' ). Any idea? Connection connection = DriverManager.getConnection("jdbc:derby://localhost:1527/PetroleumDataStorageSystemDB;create=true"); PreparedStatement statement; int i = 1; int progress = 0; for (Refuel refuelList1 : refuelList) { progress = (i / refuelList.size()) * 100; String sql = "INSERT INTO refuel (id_tank, time, fuel_volume, " +

MongoDB query to remove duplicate documents from a collection

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问题 I take data from a search box and then insert into MongoDB as a document using the regular insert query. The data is stored in a collection for the word "cancer" in the following format with unique "_id". { "_id": { "$oid": "553862fa49aa20a608ee2b7b" }, "0": "c", "1": "a", "2": "n", "3": "c", "4": "e", "5": "r" } Each document has a single word stored in the same format as above. I have many documents as such. Now, I want to remove the duplicate documents from the collection. I am unable to

How to remove duplicate items from a queue within a time frame?

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问题 I would like to remove duplicate entries from a queue in an efficient way. The queue has a custom class with DateTime and FullPath and a few other things private Queue<MyCustomClass> SharedQueue; The DateTime in the class is the timestamp when inserted into the queue. The logic I would like to use is as following: Remove duplicates from the queue if the FullPath is identical within a 4 second window (i.e. if added to queue within 4 seconds of a duplicate fullpath). I have the events that I

Python mysql check for duplicate before insert

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问题 here is the table CREATE TABLE IF NOT EXISTS kompas_url ( id BIGINT(20) NOT NULL AUTO_INCREMENT, url VARCHAR(1000), created_date datetime, modified_date datetime, PRIMARY KEY(id) ) I am trying to do INSERT to kompas_url table only if url is not exist yet any idea? thanks 回答1: You can either find out whether it's in there first, by SELECT ing by url , or you can make the url field unique: CREATE TABLE IF NOT EXISTS kompas_url ... url VARCHAR(1000) UNIQUE, ... ) This will stop MySQL from

R rbind error row.names duplicates not allowed

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There are other issues here addressing the same question, but I don't realize how to solve my problem based on it. So, I have 5 data frames that I want to merge rows in one unique data frame using rbind, but it returns the error: "Error in row.names<-.data.frame ( *tmp* , value = value) : 'row.names' duplicated not allowed In addition: Warning message: non-unique values when setting 'row.names': ‘1’, ‘10’, ‘100’, ‘1000’, ‘10000’, ‘100000’, ‘1000000’, ‘1000001 [....]" The data frames have the same columns but different number of rows. I thought the rbind command took the first column as row

Python mysql check for duplicate before insert

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here is the table CREATE TABLE IF NOT EXISTS kompas_url ( id BIGINT(20) NOT NULL AUTO_INCREMENT, url VARCHAR(1000), created_date datetime, modified_date datetime, PRIMARY KEY(id) ) I am trying to do INSERT to kompas_url table only if url is not exist yet any idea? thanks Samir Talwar You can either find out whether it's in there first, by SELECT ing by url , or you can make the url field unique: CREATE TABLE IF NOT EXISTS kompas_url ... url VARCHAR(1000) UNIQUE, ... ) This will stop MySQL from inserting a duplicate row, but it will also report an error when you try and insert. This isn't good

Prevent duplicate entries in arraylist

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问题 Say I create some object class like so public class thing { private String name; private Integer num; public oDetails (String a, Integer b) { name = a; num = b; } ...gets/ sets/ etc Now I want to create an arraylist to hold a number of this object class like so. ArrayList<thing> myList = new ArrayList<thing>; thing first = new thing("Star Wars", 3); thing second = new thing("Star Wars", 1); myList.add(first); myList.add(second); I would like to include some sort of logic so that in this case.