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  • Filtering out unique rows in MySQL

    - by jpatokal
    So I've got a large amount of SQL data that looks basically like this: user | src | dst 1 | 1 | 1 1 | 1 | 1 1 | 1 | 2 1 | 1 | 2 2 | 1 | 1 2 | 1 | 3 I want to filter out pairs of (src,dst) that are unique to one user (even if that user has duplicates), leaving behind only those pairs belonging to more than one user: user | src | dst 1 | 1 | 1 1 | 1 | 1 2 | 1 | 1 In other words, pair (1,2) is unique to user 1 and pair (1,3) to user 2, so they're dropped, leaving behind only all instances of pair (1,1). Any ideas? The answers to the question below can find the non-unique pairs, but my SQL-fu doesn't suffice to handle the complication of requiring that they belong to multiple users as well. [SQL question] How to select non "unique" rows

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  • Maddening Linked List problem

    - by Mike
    This has been plaguing me for weeks. It's something really simple, I know it. Every time I print a singly linked list, it prints an address at the end of the list. #include <iostream> using namespace std; struct node { int info; node *link; }; node *before(node *head); node *after(node *head); void middle(node *head, node *ptr); void reversep(node *head, node *ptr); node *head, *ptr, *newnode; int main() { head = NULL; ptr = NULL; newnode = new node; head = newnode; for(int c1=1;c1<11;c1++) { newnode->info = c1; ptr = newnode; newnode = new node; ptr->link = newnode; ptr = ptr->link; } ptr->link=NULL; head = before(head); head = after(head); middle(head, ptr); //reversep(head, ptr); ptr = head; cout<<ptr->info<<endl; while(ptr->link!=NULL) { ptr=ptr->link; cout<<ptr->info<<endl; } system("Pause"); return 0; } node *before(node *head) { node *befnode; befnode = new node; cout<<"What should go before the list?"<<endl; cin>>befnode->info; befnode->link = head; head = befnode; return head; } node *after(node *head) { node *afnode, *ptr2; afnode = new node; ptr2 = head; cout<<"What should go after the list?"<<endl; cin>>afnode->info; ptr2 = afnode; afnode->link=NULL; ptr2 = head; return ptr2; } void middle(node *head, node *ptr) { int c1 = 0, c2 = 0; node *temp, *midnode; ptr = head; while(ptr->link->link!=NULL) { ptr=ptr->link; c1++; } c1/=2; c1-=1; ptr = head; while(c2<c1) { ptr=ptr->link; c2++; } midnode = new node; cout<<"What should go in the middle of the list?"<<endl; cin>>midnode->info; cout<<endl; temp=ptr->link; ptr->link=midnode; midnode->link=temp; } void reversep(node *head, node *ptr) { node *last, *ptr2; ptr=head; ptr2=head; while(ptr->link!=NULL) ptr = ptr->link; last = ptr; cout<<last->info; while(ptr!=head) { while(ptr2->link!=ptr) ptr2=ptr2->link; ptr = ptr2; cout<<ptr->info; } } I'll admit that this is class work, but even the professor can't figure it out, and says that its probably something insignificant that we're overlooking, but I can't put my mind to rest until I find out what it is.

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  • Primary Key Identity Value Increments On Unique Key Constraint Violation

    - by Jed
    I have a SqlServer 2008 table which has a Primary Key (IsIdentity=Yes) and three other fields that make up a Unique Key constraint. In addition I have a store procedure that inserts a record into the table and I call the sproc via C# using a SqlConnection object. The C# sproc call works fine, however I have noticed interesting results when the C# sproc call violates the Unique Key constraint.... When the sproc call violates the Unique Key constraint, a SqlException is thrown - which is no surprise and cool. However, I notice that the next record that is successfully added to the table has a PK value that is not exactly one more than the previous record - For example: Say the table has five records where the PK values are 1,2,3,4, and 5. The sproc attempts to insert a sixth record, but the Unique Key constraint is violated and, so, the sixth record is not inserted. Then the sproc attempts to insert another record and this time it is successful. - This new record is given a PK value of 7 instead of 6. Is this normal behavior? If so, can you give me a reason why this is so? (If a record fails to insert, why is the PK index incremented?) If this is not normal behavior, can you give me any hints as to why I am seeing these symptoms?

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  • Unique SMS sender id?

    - by Pascal
    Hello, I want to build an app that send SMS to people. However, I want my users to know that the SMS comes from the app and nothing else so they can't fake it. Is there a way to guarantee that the sender ID is unique to my app? It seems that sending a SMS by phone is with a unique SENDER ID for each phone number. But, from what I read, I don't think it is the case when sending a SMS through a web gateway. Is this correct? I am not an expert in mobile phone security. Of course, I am willing to pay the price for a unique sender id, if such thing is possible. Regards, Pascal

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  • R - find and calculate with unique combinations of values

    - by lecodesportif
    I would like to work with unique combinations of var1 and var2. foo <- data.frame(var1= c(1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4), var2=c(1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 2, 3, 3)) As has been noted (+1 for answers), unique(foo) results in this: var1 var2 1 1 1 2 2 1 3 2 2 4 3 1 5 3 2 6 4 2 7 4 3 Based on the unique combinations, how do I get the number of occurrences of a var1 value and the sum (bla) of each var1 value's var2 values. The output could look like this: var1 n bla 1 1 1 1 2 2 2 3 3 3 2 3 4 4 2 5 edit: The question was too basic and probably duplicate so I extended it.

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  • SharePoint: Unique column values

    - by Anoop
    I Want to have only unique values in a SharePoin List. To achieve this I can use 'ItemAdding' event handler as mentioned in the below link. http://weblogs.asp.net/vikram/archive/2008/12/24/sharepoint-using-event-handler-to-make-a-column-unique.aspx Now I have a Doubt: Suppose that two user tries to add list Item in the list with the same column value(which requires unique value) at the same Time. will ItemAdding event would be fired at the same time for both call? If so then there is a possibility that two items having same value in the column. Please confirm.

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  • How to generate unique number of 12 digits?

    - by DanSogaard
    I'm working on an app that sends raw data to zebra printer and print out barcodes. And since every item has its own unique barcode, I need to define a variable that automatically generates unique number of 12 digits long. see example: printBar prnt = new printBar("123456789012"); Is there anyway to define a double variable and pass it to a function that return uniqely 12 digits number and pass it over again to the printBar class?. But how to make sure everytime you access it returns a unique value?. I also thought of another way, since am using MS Access db, I can create a column of AutoNumber datatype and assign it to Random, but you don't get the exact 12 digits required, sometimes it generates a value of 10 digits sometimes more or less.

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  • mysql create table help with unique

    - by Matt
    I'm trying to create a table, and can't figure out how to assign two columns to be unique.. I know how to alter a table thats already created, but how do you do it in the create.. im after a create if not exist col1 TEXT, col2 TEXT, col3 TEXT unique(col1, col2) ^very rough basic but you get the idea

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  • SQL Server: "Mostly-unique" index

    - by Ian Boyd
    In a table i want to ensure that only unique vales exist over the five-column key: Timestamp Account RatingDate TripHistoryKey EventAction ========= ======= ========== ============== =========== 2010511 1234 2010511 1 INSERT 2010511 1234 2010511 4 INSERT 2010511 1234 2010511 7 INSERT 2010511 1234 2010511 1 INSERT <---duplicate But i only want the unique constraint to apply between rows when EventAction is INSERT: Timestamp Account RatingDate TripHistoryKey EventAction ========= ======= ========== ============== =========== 2010511 1234 2010511 1 INSERT 2010511 1234 2010511 1 UPDATE 2010511 1234 2010511 1 UPDATE <---not duplicate 2010511 1234 2010511 1 UPDATE <---not duplicate 2010511 1234 2010511 1 DELETE <---not duplicate 2010511 1234 2010511 1 DELETE <---not duplicate 2010511 1234 2010511 1 INSERT <---DUPLICATE Possible?

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  • Determining if an unordered vector<T> has all unique elements

    - by Hooked
    Profiling my cpu-bound code has suggested I that spend a long time checking to see if a container contains completely unique elements. Assuming that I have some large container of unsorted elements (with < and = defined), I have two ideas on how this might be done: The first using a set: template <class T> bool is_unique(vector<T> X) { set<T> Y(X.begin(), X.end()); return X.size() == Y.size(); } The second looping over the elements: template <class T> bool is_unique2(vector<T> X) { typename vector<T>::iterator i,j; for(i=X.begin();i!=X.end();++i) { for(j=i+1;j!=X.end();++j) { if(*i == *j) return 0; } } return 1; } I've tested them the best I can, and from what I can gather from reading the documentation about STL, the answer is (as usual), it depends. I think that in the first case, if all the elements are unique it is very quick, but if there is a large degeneracy the operation seems to take O(N^2) time. For the nested iterator approach the opposite seems to be true, it is lighting fast if X[0]==X[1] but takes (understandably) O(N^2) time if all the elements are unique. Is there a better way to do this, perhaps a STL algorithm built for this very purpose? If not, are there any suggestions eek out a bit more efficiency?

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  • Determing if an unordered vector<T> has all unique elements

    - by Hooked
    Profiling my cpu-bound code has suggested I that spend a long time checking to see if a container contains completely unique elements. Assuming that I have some large container of unsorted elements (with < and = defined), I have two ideas on how this might be done: The first using a set: template <class T> bool is_unique(vector<T> X) { set<T> Y(X.begin(), X.end()); return X.size() == Y.size(); } The second looping over the elements: template <class T> bool is_unique2(vector<T> X) { typename vector<T>::iterator i,j; for(i=X.begin();i!=X.end();++i) { for(j=i+1;j!=X.end();++j) { if(*i == *j) return 0; } } return 1; } I've tested them the best I can, and from what I can gather from reading the documentation about STL, the answer is (as usual), it depends. I think that in the first case, if all the elements are unique it is very quick, but if there is a large degeneracy the operation seems to take O(N^2) time. For the nested iterator approach the opposite seems to be true, it is lighting fast if X[0]==X[1] but takes (understandably) O(N^2) time if all the elements are unique. Is there a better way to do this, perhaps a STL algorithm built for this very purpose? If not, are there any suggestions eek out a bit more efficiency?

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  • Doubt in action script for Flex: getting unique elements from an ArrayCollection

    - by Nirmal Singh Raja Reegan
    Hi, I have an ArrayCollection as mentioned below. private var initDG:ArrayCollection = new ArrayCollection([ {fact: "Order #2314", appName: "AA"}, {fact: "Order #2315", appName: "BB"} {fact: "Order #2316", appName: "BB"} ... {fact: "Order #2320", appName: "CC"} {fact: "Order #2321", appName: "CC"} ]); I want to populate a ComboBox with UNIQUE VALUES of "appName" field from the ArrayCollection initDG. <mx:ComboBox id="appCombo" dataProvider="{initDG}" labelField="appName"/> One method I could think is to loop through the Array objects and for each object check and push unique appName entries into another Array. Is there any better solution available?

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  • Unique items in Hibernate collections

    - by Rickard Lindberg
    I have defined a collection in Hibernate like this: ... public class Item { ... @ElementCollection List<Object> relatedObjects; } It creates a mapping table with colums item_id and object_id. The problem is that object_id seems to be unique. In other words I can not have two different items being related to the same object. But that is what I want. I would like the combination of item_id and object_id to be unique. How do I do that?

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  • Check For Duplicate Records VS try/catch Unique Key Constraint

    - by Jed
    I have a database table that has a Unique Key constraint defined to avoid duplicate records from occurring. I'm curious if it is bad practice to NOT manually check for duplicate records prior to running an INSERT statement on the table. In other words, should I run a SELECT statement using a WHERE clause that checks for duplicate values of the record that I am about to INSERT. If a record is found, then do not run the INSERT statement, otherwise go ahead and run the INSERT.... OR Just run the INSERT statement and try/catch the exception that may be thrown due to a Unique Key violation. I'm weighing the two perspectives and can't decide which is best- 1. Don't waste a SELECT call to check for duplicates when I can just trap for an exception VS 2. Don't be lazy by implementing ugly try/catch logic VS 3. ???Your thoughts here??? :)

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  • Rails uniqueness constraint and matching db unique index for null column

    - by Dave
    I have the following in my migration file def self.up create_table :payment_agreements do |t| t.boolean :automatic, :default => true, :null => false t.string :payment_trigger_on_order t.references :supplier t.references :seller t.references :product t.timestamps end end I want to ensure that if a product_id is specified it is unique but I also want to allow null so I have the following in my model: validates :product_id, :uniqueness => true, :allow_nil => true Works great but I should then add an index to the migration file add_index :payment_agreements, :product_id, :unique => true Obviously this will throw an exception when two null values are inserted for product_id. I could just simply omit the index in the migration but then there's the chance that I'll get two PaymentAgreements with the same product_id as shown here: Concurrency and integrity My question is what is the best/most common way to deal with this problem

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  • Creating a unique key based on file content in python

    - by Cawas
    I got many, many files to be uploaded to the server, and I just want a way to avoid duplicates. Thus, generating a unique and small key value from a big string seemed something that a checksum was intended to do, and hashing seemed like the evolution of that. So I was going to use hash md5 to do this. But then I read somewhere that "MD5 are not meant to be unique keys" and I thought that's really weird. What's the right way of doing this? edit: by the way, I took two sources to get to the following, which is how I'm currently doing it and it's working just fine, with Python 2.5: import hashlib def md5_from_file (fileName, block_size=2**14): md5 = hashlib.md5() f = open(fileName) while True: data = f.read(block_size) if not data: break md5.update(data) f.close() return md5.hexdigest()

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  • T-SQL Unique constraint locked the SQL server

    - by PaN1C_Showt1Me
    HI ! This is my table: CREATE TABLE [ORG].[MyTable]( .. [my_column2] UNIQUEIDENTIFIER NOT NULL CONSTRAINT FK_C1 REFERENCES ORG.MyTable2 (my_column2), [my_column3] INT NOT NULL CONSTRAINT FK_C2 REFERENCES ORG.MyTable3 (my_column3) .. ) I've written this constraint to assure that combination my_column2 and my_column3 is always unique. ALTER TABLE [ORG].[MyTable] ADD CONSTRAINT UQ_MyConstraint UNIQUE NONCLUSTERED ( my_column2, my_column3 ) But then suddenly.. The DB stopped responding.. there is a lock or something.. Do you have any idea why? What is bad with the constraint?

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  • Unique constraint not created in JPA

    - by homaxto
    I have created the following entity bean, and specified two columns as being unique. Now my problem is that the table is created without the unique constraint, and no errors in the log. Does anyone have an idea? @Entity @Table(name = "cm_blockList", uniqueConstraints = @UniqueConstraint(columnNames = {"terminal", "blockType"})) public class BlockList { @Id @GeneratedValue(strategy = GenerationType.AUTO) private int id; @ManyToOne(cascade = CascadeType.PERSIST) @JoinColumn(name="terminal") private Terminal terminal; @Enumerated(EnumType.STRING) private BlockType blockType; private String regEx; }

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  • Unique constraint on more than 10 columns

    - by tk
    I have a time-series simulation model which has more than 10 input variables. The number of distinct simulation instances would be more than 1 million, and each simulation instance generates a few output rows every day. To save the simulation result in a relational database, i designed tables like this. Table SimulationModel { simul_id : integer (primary key), input0 : string or numeric, input1 : string or numeric, ...} Table SimulationOutput { dt : DateTime (primary key), simul_id : integer (primary key), output0 : numeric, ...} My question is, is it fine to put an unique constraint on all of the input columns of SimulationModel table? If it is not a good idea, then what kind of other options do i have to make sure each model is unique?

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  • jQuery: how to pick unique IDs ?

    - by Seerumi
    Hello. New to whole this jQuery (and javascript altogether, heh) and so far it's been excellent, but now I'm in a small pickle. Let's say I have list of forms generated from SQL database and every single one of them has to have unique id, so how I can select the specific item that is to be manipulated (changing values via php). the $("#submit").click(function()) will trigger every submit buttons on the page, so how I can the #submit to be some random id that I clicked. There might be a smarter way, but I'm new to this so try to bear with me. thought of passing the unique value with onClick="myfunction(unique_id)", but don't know how it goes with jQuery. hope this made any sense

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  • How is precedence determined in C pointers?

    - by ankur.trapasiya
    I've come across two pointer declarations that I'm having trouble understanding. My understanding of precedence rules goes something like this: Operator Precedence Associativity (), [ ] 1 Left to Right *, identifier 2 Right to Left Data type 3 But even given this, I can't seem to figure out how to evaluate the following examples correctly: First example float * (* (*ptr)(int))(double **,char c) My evaluation: *(ptr) (int) *(*ptr)(int) *(*(*ptr)(int)) Then, double ** char c Second example unsigned **( * (*ptr) [5] ) (char const *,int *) *(ptr) [5] *(*ptr)[5] *(*(*ptr)[5]) **(*(*ptr)[5]) How should I read them?

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  • does ping command to a dns name uses DNS PTR type messages?

    - by TiagoM
    Okay I cant understand this, when I try to ping to a machine on my network using the name associated I get a response from that machine, thats normal.. But there are messages that the sender sends to the top machine (SOA) that I dont understand.. First he sends a type A and gets a response with the IP associated to the name used on the ping command, but after that.. the sender only sends (before each ping) messages of type PTR to the (SOA) Saying this: Standar query 0xf66c PTR 12.45.168.192.in-addr.arpa and SOA respond with: Standard query response 0xf66c No such name And before each ping they do this, I dont know why... I notice this using wireshark, thanks alot again for accept me here, being able to get some answer :)

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