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  • Merge two rows in SQL

    - by Jason
    Assuming I have a table containing the following information: FK | Field1 | Field2 ===================== 3 | ABC | *NULL* 3 | *NULL* | DEF is there a way I can perform a select on the table to get the following FK | Field1 | Field2 ===================== 3 | ABC | DEF Thanks Edit: Fix field2 name for clarity

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  • Reducing Time Complexity in Java

    - by Koeneuze
    Right, this is from an older exam which i'm using to prepare my own exam in january. We are given the following method: public static void Oorspronkelijk() { String bs = "Dit is een boodschap aan de wereld"; int max = -1; char let = '*'; for (int i=0;i<bs.length();i++) { int tel = 1; for (int j=i+1;j<bs.length();j++) { if (bs.charAt(j) == bs.charAt(i)) tel++; } if (tel > max) { max = tel; let = bs.charAt(i); } } System.out.println(max + " keer " + let); } The questions are: what is the output? - Since the code is just an algorithm to determine the most occuring character, the output is "6 keer " (6 times space) What is the time complexity of this code? Fairly sure it's O(n²), unless someone thinks otherwise? Can you reduce the time complexity, and if so, how? Well, you can. I've received some help already and managed to get the following code: public static void Nieuw() { String bs = "Dit is een boodschap aan de wereld"; HashMap<Character, Integer> letters = new HashMap<Character, Integer>(); char max = bs.charAt(0); for (int i=0;i<bs.length();i++) { char let = bs.charAt(i); if(!letters.containsKey(let)) { letters.put(let,0); } int tel = letters.get(let)+1; letters.put(let,tel); if(letters.get(max)<tel) { max = let; } } System.out.println(letters.get(max) + " keer " + max); } However, I'm uncertain of the time complexity of this new code: Is it O(n) because you only use one for-loop, or does the fact we require the use of the HashMap's get methods make it O(n log n) ? And if someone knows an even better way of reducing the time complexity, please do tell! :)

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  • How can I sort a Perl array of array of hashes?

    - by srk
    @aoaoh; $aoaoh[0][0]{21} = 31; $aoaoh[0][0]{22} = 31; $aoaoh[0][0]{23} = 17; for $k (0 .. $#aoaoh) { for $i(0.. $#aoaoh) { for $val (keys %{$aoaoh[$i][$k]}) { print "$val=$aoaoh[$i][$k]{$val}\n"; } } } The output is: 22=31 21=31 23=17 but i expect it to be 21=31 22=31 23=17 Please tell me where is this wrong. Also how do I sort the values so that i get the output as 23=17 22=31 21=31 (if 2 keys have same value then key with higher value come first)

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  • SQL query through an intermediate table

    - by Bryan
    Given the following tables: Recipes | id | name | 1 | 'chocolate cream pie' | 2 | 'banana cream pie' | 3 | 'chocolate banana surprise' Ingredients | id | name | 1 | 'banana' | 2 | 'cream' | 3 | 'chocolate' RecipeIngredients | recipe_id | ingredient_id | 1 | 2 | 1 | 3 | 2 | 1 | 2 | 2 | 3 | 1 | 3 | 3 How do I construct a SQL query to find recipes where ingredients.name = 'chocolate' and ingredients.name = 'cream'?

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  • Freebase Query with "JOINS"

    - by codemonkey
    ... Yeah, yeah, I know traditional joins don't exist. I actually like the freebase query methodology in theory, just having a little trouble getting it to actually work for me : ) Anyone have a dumb-simple example of getting Freebase data via MQL that pulls from two different "tables"? In particular, I'm trying to get automotive data... so for example, pulling fields from both /automotive/model_year and /automotive/trim_year. I've read the documentation (for hours actually). There's a distinct possibility that I'm looking right at such an example somewhere and just not seeing it because my OLTP brain just doesn't comprehend what it's seeing. * Note * ... that the two "types" I'm working with above are siblings, not parent/child. Does freebase even allow joining data between sibling nodes... I see examples of queries pulling from parent/child, but not from siblings I don't think (or I've overlooked them).

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  • MySQL Select statement Where table1.id != table2.id

    - by Michael
    I have a table of data which has posts, then I have a separate table of data which has deleted posts. What happens when a post is deleted is that it's ID get's added to the deleted table rather than removing the post entry. What is a clean efficient way of selecting all the posts from the posts table without selecting the ones that have their ID in the deleted table

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  • Inner join on 2 arrays?

    - by russ
    I'm trying to find a solution to the following (I'm thinking with Linq) to the following: I need to pull down certain files from a larger list of files on an ftp server that have a similar file name. For example, we send an order file to some company for processing then they return a response file that we can download. So, I could send them the files "order_123.txt" and "order_456.txt". After a certain amount of time I need to go look for and download the responses for those files that will be named "order_123.resp" and "order_456.resp". The kicker is that in some cases I can have multiple responses in which case they would create "order_123-1.resp" and "order_123-2.resp" and also the files don't get removed from the server. I know this can be accomplished by looping through the files I know I need responses to then loop through all the files on the server until I find files that match but I'm hoping that I don't have to loop through the files on the server more than once. This example may help clarify: I've sent "order_222.txt" and "order_333.txt" they processed them and the ftp server contains: "order_111-1.resp" "order_001.resp" "order_222-1.resp" "order_222-2.resp" "order_333.resp" I need to download the 3rd, 4th, and 5th file. Thanks.

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  • MySQL query pulling from two tables, display in correct fields

    - by Matt Nathanson
    I'm trying to select all fields in two separate tables as long as they're sharing a common ID. //mysql query $result = mysql_query("SELECT * FROM project, links WHERE project.id = links.id and project.id = $clientID") //displaying the link if ($row['url'] != null){ echo "<div class='clientsection' id='links'>Links</div>"; echo "<a class='clientlink' id='link1' href='" . $row['url'] . "'>" . $row['name'] . "</a>"; } else { echo "<a class='clientlink' id='link1' href='" . $row['url'] . "' style='display:none;'>" . $row['name'] . "</a>"; }; As you can see, my tables are "projects", and "links" Each is sharing a common field "id" for reference. It looks as though where both links.id and project.id are equal, it outputs anything, but when there is no links.id associated with a given $clientID the container relative to the $clientID doesn't display at all. Essentially I'm using this to add links dynamically to a specific client in this CMS and if there are no links, I want the container to show up anyway. Hopefully I've expressed myself clearly, any pointers in the right direction are appreciated. Thanks!

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  • Treat multiple IEnumerable objects as a single IEnumerable

    - by MainMa
    Hi, My question seems to be something easy, but I can't figure it out. Let's say I have a "root" IEnumerable of objects. Each object has IEnumerable of strings. How can I obtain a single IEnumerable of those strings? A possible solution is to do: public IEnumerable<string> DoExample() { foreach (var c in rootSetOfObjects) { foreach (var n in c.childSetOfStrings) { yield return n; } } } But maybe there is a magic solution with Linq?

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  • Why this code generates different numbers?

    - by frbry
    Hello, I have this function that creates a unique number for hard-disk and CPU combination. DWORD hw_hash() { char drv[4]; char szNameBuffer[256]; DWORD dwHddUnique; DWORD dwProcessorUnique; DWORD dwUniqueKey; char *sysDrive = getenv ("SystemDrive"); strcpy(drv, sysDrive); drv[2] = '\\'; drv[3] = 0; GetVolumeInformation(drv, szNameBuffer, 256, &dwHddUnique, NULL, NULL, NULL, NULL); SYSTEM_INFO si; GetSystemInfo(&si); dwProcessorUnique = si.dwProcessorType + si.wProcessorArchitecture + si.wProcessorRevision; dwUniqueKey = dwProcessorUnique + dwHddUnique; return dwUniqueKey; } It returns different numbers if I format my hard-disk and install a new Windows. Any ideas, why? Thank you. Edit: OK, Got it: This function returns the volume serial number that the operating system assigns when a hard disk is formatted. To programmatically obtain the hard disk's serial number that the manufacturer assigns, use the Windows Management Instrumentation (WMI) Win32_PhysicalMedia property SerialNumber. I should do more research before posting my problems online. Sorry to bother you, let's keep this here in case anybody else can need it.

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  • SQLite join selection from the same table using reference from another table

    - by daikini
    I have two tables: table: points |key_id | name | x | y | ------------------------ |1 | A |10 |20 | |2 | A_1 |11 |21 | |3 | B |30 |40 | |4 | B_1 |31 |42 | table: pairs |f_key_p1 | f_key_p2 | ---------------------- |1 | 2 | |3 | 4 | Table 'pairs' defines which rows in table 'points' should be paired. How can I query database to select paired rows? My desired query result would be like this: |name_1|x_1|x_2|name_2|x_2|y_2| ------------------------------- |A |10 |20 |A_1 |11 |21 | |B |30 |40 |B_1 |31 |41 |

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  • Minimizing SQL queries using join with one-to-many relationship

    - by Brian
    So let me preface this by saying that I'm not an SQL wizard by any means. What I want to do is simple as a concept, but has presented me with a small challenge when trying to minimize the amount of database queries I'm performing. Let's say I have a table of departments. Within each department is a list of employees. What is the most efficient way of listing all the departments and which employees are in each department. So for example if I have a department table with: id name 1 sales 2 marketing And a people table with: id department_id name 1 1 Tom 2 1 Bill 3 2 Jessica 4 1 Rachel 5 2 John What is the best way list all departments and all employees for each department like so: Sales Tom Bill Rachel Marketing Jessica John Pretend both tables are actually massive. (I want to avoid getting a list of departments, and then looping through the result and doing an individual query for each department). Think similarly of selecting the statuses/comments in a Facebook-like system, when statuses and comments are stored in separate tables.

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  • Simplifying and reducing the cost of an anti-join query

    - by Savitha
    Hi, Could you please help me in simplifying and reducing the cost of the below query? I tried making it a co-related subquery with NOT EXISTS but it didn't give me any output. Please note that the table in both main and inner query is the same 'table_1". SELECT * FROM Table_1 A WHERE A.Col1 = 'abcd' AND (A.Col2, A.Col3) NOT IN (SELECT Col2, Col3 FROM Table_1 B WHERE (B.Col4 IN (1,2,3) And B.Col5 In ('x','y')) OR (B.Col4 = 1 AND B.Col5 = 'z' AND B.Col6 = 'f') )) Thanks in advance, Savitha

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  • Oracle Procedure to join two tables with latest status

    - by Sony
    Please help me make an oracle stored procedure ; I have two tables tblLead: lead_id Name 1 x 2 y 3 z tblTransaction: Tran_id lead_id date status 1 1 04/20/2010 call Later 2 1 05/05/2010 confirmed I want a result like lead_id Name status 1 x confirmed 2 y not available ! 3 z not available !

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  • Good PHP / MYSQL hashing solution for large number of text values

    - by Dave
    Short descriptio: Need hashing algorithm solution in php for large number of text values. Long description. PRODUCT_OWNER_TABLE serial_number (auto_inc), product_name, owner_id OWNER_TABLE owner_id (auto_inc), owener_name I need to maintain a database of 200000 unique products and their owners (AND all subsequent changes to ownership). Each product has one owner, but an owner may have MANY different products. Owner names are "Adam Smith", "John Reeves", etc, just text values (quite likely to be unicode as well). I want to optimize the database design, so what i was thinking was, every week when i run this script, it fetchs the owner of a proudct, then checks against a table i suppose similar to PRODUCT_OWNER_TABLE, fetching the owner_id. It then looks up owner_id in OWNER_TABLE. If it matches, then its the same, so it moves on. The problem is when its different... To optimize the database, i think i should be checking against the other "owner_name" entries in OWNER_TABLE to see if that value exists there. If it does, then i should use that owner_id. If it doesnt, then i should add another entry. Note that there is nothing special about the "name". as long as i maintain the correct linkagaes AND make the OWNER_TABLE "read-only, append-new" type table - I should be able create a historical archive of ownership. I need to do this check for 200000 entries, with i dont know how many unique owner names (~50000?). I think i need a hashing solution - the OWNER_TABLE wont be sorted, so search algos wont be optimal. programming language is PHP. database is MYSQL.

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  • Help with grasping (INNER?) JOIN

    - by Greenie
    I'm having trouble building a query. I can do what I want in 3 different queries. SELECT id FROM table1 WHERE url LIKE '%/$downloadfile' put that in $url_id SELECT item_id FROM table2 WHERE rel_id = '$url_id'" put that in $item_id SELECT rel_id FROM table2 WHERE rel_id = '$item_id' AND field_id = '42'" put that in $user_id But from reading examples on joins and inner joins I think there's a more elegant way. I cant wrap my brain around writing a better query (but would like to) I can describe how it should go: table1 fields: id, url table2 fields item_id, rel_id, field_id I know the last part of table1.url (LIKE '%/$filename') with that I select table1.id. table1.id is equal to one entry in table2.rel_id. So get that and select the table2.item_id. In table2 there is another entry which has the same table2.item_id and it will have a table2.field_id = '42' And finally the value I need is the table2.rel_id where the table2.field_id was 42. I will fetch that value and put it in $user_id Can this be done with one query using joins/inner joins?

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  • MongoDB - how to join parent and child products by reference

    - by Jaro
    my mongo collection stores products. There are two product types: child and parent. Parent product holds array of its child as reference. Use case: use mydb; child1 = { _id: 1, name: "Child 1", is_child: true, is_parent: false, children : [] } child2 = { _id: 2, name: "Child 2", is_child: true, is_parent: false, children : [] } parent = { _id: 3, name: "Parent product", is_child: false, is_parent: true, children : [1, 2] } db.product.insert( [child1, child2, parent] ); And I'm looking for any query returning { _id: 3, name: "Parent product", is_child: false, is_parent: true, children: [ { _id: 1, name: "Child 1", is_child: true, is_parent: false, children : [] }, { _id: 2, name: "Child 2", is_child: true, is_parent: false, children : [] } ] } I'm newbie to mongodb, but I guess an usage of map-reduce could solve the problem. Can anyone advice? Thx

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  • Mapping words to numbers with respect to definition

    - by thornate
    As part of a larger project, I need to read in text and represent each word as a number. For example, if the program reads in "Every good boy deserves fruit", then I would get a table that converts 'every' to '1742', 'good' to '977513', etc. Now, obviously I can just use a hashing algorithm to get these numbers. However, it would be more useful if words with similar meanings had numerical values close to each other, so that 'good' becomes '6827' and 'great' becomes '6835', etc. As another option, instead of a simple integer representing each number, it would be even better to have a vector made up of multiple numbers, eg (lexical_category, tense, classification, specific_word) where lexical_category is noun/verb/adjective/etc, tense is future/past/present, classification defines a wide set of general topics and specific_word is much the same as described in the previous paragraph. Does any such an algorithm exist? If not, can you give me any tips on how to get started on developing one myself? I code in C++.

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  • LINQ Join for Orderby only

    - by RandomBen
    I am trying to run this code: ItemTaxonomy iTaxonomy = from itemTaxonomy in connection.ItemTaxonomy where itemTaxonomy.Item.ID == itemView.ID orderby itemTaxonomy.Taxonomy.Name select itemTaxonomy; When I compiled it I get the error: Cannot implicitly convert type 'System.Linq.IOrderedQueryable<Website.Models.ItemTaxonomy>' to 'Website.Models.ItemTaxonomy'. An explicit conversion exists (are you missing a cast?) I believe the issue is with orderby itemTaxonomy.Taxonomy.Name but I am just trying to order by the name of Taxonomy items instead of their IDs. Is there a way to do that?

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  • SQL How to join multiplue columns with same name to one column

    - by Choi Shun Chi
    There is a super class account {User, TYPE} and subclasses saving{User, ID, balance,TYPE,interest,curency_TYPE} time{User,ID,balance,TYPE,interest,curency_TYPE,start_date,due_date,period} fore{User,ID,balance,interest,curency_TYPE} User and TYPE is the primary key of account and foreign key of three subclasses ID is primary key of three subclasses how to make a list of showing all IDs in one column?Also the same as balance and TYPE meet the problem I considered a.ID as saving, b.ID as time but it showing them separately

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  • SQL join to grab data from same table via intermediate table

    - by Sergio
    Hi Could someone help me with building the following query. I have a table called Sites, and one called Site_H. The two are joined by a foreign key relationship on page_id. So the Sites table contains pages, and the Site_H table shows which pages any given page is a child of by having another foreign key relation back to the site table with a column called ParentOf. So, a page can be have another page as a parent. Other data is stored in the Site_H table such as position etc, hence why it is separated out. I would like a query that returns the details of a page along with the details of its parent page. I just cant quite think about how to structure the SQL. Thanks

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  • What is a SQL statement that can tally up the counts even including the Zeros? (all in 1 statement)

    - by Jian Lin
    A SQL statement can give a list of the most popular gifts that are sent in a Social application, all the way to the ones that are sent 1, or 2 times, but it won't include the Zeros. I think the same goes for getting the list of the most popular Classes that students are registering for, when the registration process for all students is 10 days and now it is the 3rd day. Again, we get the count but the Zeros are not there. Is there a simple SQL statement that can show the whole list, including the zeros?

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  • Oracle (Old?) Joins

    - by Grasper
    I have been porting oracle selects, and I have been running across a lot of queries like so: SELECT e.last_name, d.department_name FROM employees e, departments d WHERE e.department_id(+) = d.department_id; ...and: SELECT last_name, d.department_id FROM employees e, departments d WHERE e.department_id = d.department_id(+); Are there any guides/tutorials for converting all of the variants of the (+) syntax? What is that syntax even called (so I can scour google)? When was this standard phased out? Any info is appreciated.

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  • Java - Make an object collection friendly

    - by DutrowLLC
    If an object holds a unique primary key, what interfaces does it need to implement in order to be collection friendly especially in terms of being efficiently sortable, hashable, etc...? If the primary key is a string, how are these interfaces best implemented? Thanks!

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