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  • sql unite fields to one result

    - by none
    i know this is a "not build in" or "the way dba thinks" but a programmer aproach , How could one request from 3 fields to get the one that is not null, into a result filed. lets say we have a table with f1,f2,f3,f4,f5. lets say f2,f3,f4 are the same type. lets say the content of the table be tupples of (key1,null,null,value1,value2) (key2,null,value3,value4,value5) (key3,null,null,null,value6) now if we return the first tupple then we get (key1) we get (key1,value1,value2) if we ask for key2 we get (key1,value3,value5) if we ask for key3 we get (key1,null,value6) how is it possible to get the fields in the priority of if you have value in f2, then its set into the returned field, only then if we have value in f3 then its set into the middle returned field, only then if we have value in f4 then its set into the middle returned field the main goal is to get the result into a sigel feild and prevent the overhead work needed at the result end.

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  • duplicate record

    - by user349953
    Insert into Attendancemst ( emp_code , name, date , timetable , on_duty,out_duty,clockin , clockout, late, early, mis_in , mis_out , absent , halfday, total_time ) values (pemp_code,pname,pdate,ptimetable,pon_duty,pout_duty ,pclockin,pclockout,plate, pearly, pmis_in,pmis_out,pabsent,phalfday,ptotal_time )ON DUPLICATE KEY UPDATE emp_code=pemp_code and date = pdate;

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  • Concate String In MYSQL

    - by streetparade
    How can i concate this string in mysql desc=desc+$desct what i want is each time i insert a variable from PHP that the string is added to the string which was already in db and seperated with || the field desc should look like this desc 10||30||90||710 say i want to add the value 20 desc 10||30||90||710||20 then the desc field should look like this How can i implement this?

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  • html escape characters

    - by user1468537
    I have the following: <form name="input" method="get" action="http://site:8083/Default.aspx?DC=" target="foo" onSubmit="window.open('', 'foo', 'width=1100 height=500,status=no,resizable=yes,scrollbars=yes')"> <select name="DC"> <option value="1&Type=type1">1</option> <option value="2&Type=type2">2</option> <option value="3&Type=type3">3</option> <option value="4&Type=type4">4</option> <option value="5&Type=type5">5</option> <option value="6&Type=type6">6</option> <option value="7&Type=type7">7</option> </select> <input type="submit" value=">>"/>&nbsp;&nbsp; </form> Basically my querystring should be something like DC=1&Type=type1 the problem I have is that when I click the button above the html screws up the stirng by changing & to %26 and = to %3D How can I make the value stay as I have it in the code above?

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  • Beginner having difficulty with SQL query

    - by Vulcanizer
    Hi, I've been studying SQL for 2 weeks now and I'm preparing for an SQL test. Anyway I'm trying to do this question: For the table: 1 create table data { 2 id int, 3 n1 int not null, 4 n2 int not null, 5 n3 int not null, 6 n4 int not null, 7 primary key (id) 8 } I need to return the relation with tuples (n1, n2, n3) where all the corresponding values for n4 are 0. The problem asks me to solve it WITHOUT using subqueries(nested selects/views) It also gives me an example table and the expected output from my query: 01 insert into data (id, n1, n2, n3, n4) 02 values (1, 2,4,7,0), 03 (2, 2,4,7,0), 04 (3, 3,6,9,8), 05 (4, 1,1,2,1), 06 (5, 1,1,2,0), 07 (6, 1,1,2,0), 08 (7, 5,3,8,0), 09 (8, 5,3,8,0), 10 (9, 5,3,8,0); expects (2,4,7) (5,3,8) and not (1,1,2) since that has a 1 in n4 in one of the cases. The best I could come up with was: 1 SELECT DISTINCT n1, n2, n3 2 FROM data a, data b 3 WHERE a.ID <> b.ID 4 AND a.n1 = b.n1 5 AND a.n2 = b.n2 6 AND a.n3 = b.n3 7 AND a.n4 = b.n4 8 AND a.n4 = 0 but I found out that also prints (1,1,2) since in the example (1,1,2,0) happens twice from IDs 5 and 6. Any suggestions would be really appreciated.

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  • How to output multiple rows from an SQL query using the mysqli object

    - by Jonathan
    Assuming that the mysqli object is already instantiatied (and connected) with the global variable $mysql, here is the code I am trying to work with. class Listing { private $mysql; function getListingInfo($l_id = "", $category = "", $subcategory = "", $username = "", $status = "active") { $condition = "`status` = '$status'"; if (!empty($l_id)) $condition .= "AND `L_ID` = '$l_id'"; if (!empty($category)) $condition .= "AND `category` = '$category'"; if (!empty($subcategory)) $condition .= "AND `subcategory` = '$subcategory'"; if (!empty($username)) $condition .= "AND `username` = '$username'"; $result = $this->mysql->query("SELECT * FROM listing WHERE $condition") or die('Error fetching values'); $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; return $info; } } there are several hundred listings in the db and when I call $result-fetch_array() it places in an array the first row in the db. however when I try to call the object, I can't seem to access more than the first row. for instance: $listing_row = new Listing; while ($listing = $listing_row-getListingInfo()) { echo $listing[0]; } this outputs an infinite loop of the same row in the db. Why does it not advance to the next row? if I move the code: $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; if I move this outside the class, it works exactly as expected outputting a row at a time while looping through the while statement. Is there a way to write this so that I can keep the fetch_array() call in the class and still loop through the records?

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  • Example of user-defined integrity rule in database systems?

    - by Pavel
    Hey everyone. I'm currently preparing for my exams and would like to know some examples of user-defined integrity rule in database systems. As far as I understand, it means that I can set up certain conditions for the columns and when data is inserted it needs to fulfill these conditions. For example: if I set up a rule that an ID needs to consist of 5 integers ONLY then when I insert a row with ID which is made up of integers and some chars then it won't accept it and return an error. Could someone confirm and give me some opinion on that? Thank you very much in advance!

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  • 'Good' programming form in maintaining / updating / accessing files by entry

    - by zhermes
    Basic Question: If I'm storying/modifying data, should I access elements of a file by index hard-coded index, i.e. targetFile.getElement(5); via a hardcoded identifier (internally translated into index), i.e. target.getElementWithID("Desired Element"), or with some intermediate DESIRED_ELEMENT = 5; ... target.getElement(DESIRED_ELEMENT), etc. Background: My program (c++) stores data in lots of different 'dataFile's. I also keep a list of all of the data-files in another file---a 'listFile'---which also stores some of each one's properties (see below, but i.e. what it's name is, how many lines of information it has etc.). There is an object which manages the data files and the list file, call it a 'fileKeeper'. The entries of a listFile look something like: filename , contents name , number of lines , some more numbers ... Its definitely possible that I may add / remove fields from this list --- but in general, they'll stay static. Right now, I have a constant string array which holds the identification of each element in each entry, something like: const string fileKeeper::idKeys[] = { "FileName" , "Contents" , "NumLines" ... }; const int fileKeeper::idKeysNum = 6; // 6 - for example I'm trying to manage this stuff in 'good' programatic form. Thus, when I want to retrieve the number of lines in a file (for example), instead of having a method which just retrieves the '3'rd element... Instead I do something like: string desiredID = "NumLines"; int desiredIndex = indexForID(desiredID); string desiredElement = elementForIndex(desiredIndex); where the function indexForID() goes through the entries of idKeys until it finds desiredID then returns the index it corresponds to. And elementForIndex(index) actually goes into the listFile to retrieve the index'th element of the comma-delimited string. Problem: This still seems pretty ugly / poor-form. Is there a way I should be doing this? If not, what are some general ways in which this is usually done? Thanks!

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  • Are doubles faster than floats in c#?

    - by Trap
    I'm writing an application which reads large arrays of floats and performs some simple operations with them. I'm using floats because I thought it'd be faster than doubles, but after doing some research I've found that there's some confusion about this topic. Can anyone elaborate on this? Thanks.

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  • Are conditional subqueries optimized out, if the condition is false?

    - by Tobias Schulte
    I have a table foo and a table bar, where each foo might have a bar (and a bar might belong to multiple foos). Now I need to select all foos with a bar. My sql looks like this SELECT * FROM foo f WHERE [...] AND ($param IS NULL OR (SELECT ((COUNT(*))>0) FROM bar b WHERE f.bar = b.id)) with $param being replaced at runtime. The question is: Will the subquery be executed even if param is null, or will the dbms optimize the subquery out? We are using mysql, mssql and oracle. Is there a difference between these regarding the above?

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  • Rails: How can I log all requests which take more than 4s to execute?

    - by Fedyashev Nikita
    I have a web app hosted in a cloud environment which can be expanded to multiple web-nodes to serve higher load. What I need to do is to catch this situation when we get more and more HTTP requests (assets are stored remotely). How can I do that? The problem I see from this point of view is that if we have more requests than mongrel cluster can handle then the queue will grow. And in our Rails app we can only count only after mongrel will receive the request from balancer.. Any recommendations?

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  • Optimizing Code

    - by Claudiu
    You are given a heap of code in your favorite language which combines to form a rather complicated application. It runs rather slowly, and your boss has asked you to optimize it. What are the steps you follow to most efficiently optimize the code? What strategies have you found to be unsuccessful when optimizing code? Re-writes: At what point do you decide to stop optimizing and say "This is as fast as it'll get without a complete re-write." In what cases would you advocate a simple complete re-write anyway? How would you go about designing it?

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  • Execute multiple queries

    - by smartali89
    I am using OleDB for executing my queries in C#, Is there any way I can execute multiple queries in one command statement? I tried to separate them with semi-colon (;) but it gives error "Characters found at the end" I have to execute a few hundreds of queries at once.

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  • Strange profiler behavior: same functions, different performances

    - by arthurprs
    I was learning to use gprof and then i got weird results for this code: int one(int a, int b) { return a / (b + 1); } int two(int a, int b) { return a / (b + 1); } int main() { for (int i = 1; i < 30000000; i++) { two(i, i * 2); one(i, i * 2); } return 0; } and this is the profiler output % cumulative self self total time seconds seconds calls ns/call ns/call name 48.39 0.90 0.90 29999999 30.00 30.00 one(int, int) 40.86 1.66 0.76 29999999 25.33 25.33 two(int, int) 10.75 1.86 0.20 main If i call one then two the result is the inverse, two takes more time than one both are the same functions, but the first calls always take less time then the second Why is that? Note: The assembly code is exactly the same and code is being compiled with no optimizations

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  • Intersection() and Except() is too slow with large collections of custom objects

    - by Theo
    I am importing data from another database. My process is importing data from a remote DB into a List<DataModel> named remoteData and also importing data from the local DB into a List<DataModel> named localData. I am then using LINQ to create a list of records that are different so that I can update the local DB to match the data pulled from remote DB. Like this: var outdatedData = this.localData.Intersect(this.remoteData, new OutdatedDataComparer()).ToList(); I am then using LINQ to create a list of records that no longer exist in remoteData, but do exist in localData, so that I delete them from local database. Like this: var oldData = this.localData.Except(this.remoteData, new MatchingDataComparer()).ToList(); I am then using LINQ to do the opposite of the above to add the new data to the local database. Like this: var newData = this.remoteData.Except(this.localData, new MatchingDataComparer()).ToList(); Each collection imports about 70k records, and each of the 3 LINQ operation take between 5 - 10 minutes to complete. How can I make this faster? Here is the object the collections are using: internal class DataModel { public string Key1{ get; set; } public string Key2{ get; set; } public string Value1{ get; set; } public string Value2{ get; set; } public byte? Value3{ get; set; } } The comparer used to check for outdated records: class OutdatedDataComparer : IEqualityComparer<DataModel> { public bool Equals(DataModel x, DataModel y) { var e = string.Equals(x.Key1, y.Key1) && string.Equals(x.Key2, y.Key2) && ( !string.Equals(x.Value1, y.Value1) || !string.Equals(x.Value2, y.Value2) || x.Value3 != y.Value3 ); return e; } public int GetHashCode(DataModel obj) { return 0; } } The comparer used to find old and new records: internal class MatchingDataComparer : IEqualityComparer<DataModel> { public bool Equals(DataModel x, DataModel y) { return string.Equals(x.Key1, y.Key1) && string.Equals(x.Key2, y.Key2); } public int GetHashCode(DataModel obj) { return 0; } }

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  • why use the "!!!"?

    - by lazyanno
    as follow codes: var a = {}; if(!!!a[tabType]){ a[tabType] = []; a[tabType].push([self,boxObj]); }else{ a[tabType].push([self,boxObj]); } i think !!!a[tabType] equals !a[tabType] why use the "!!!" not "!" ? thank you!

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  • Best practice for avoiding locks on a heavily read table?

    - by Luiggi
    Hi, I have a big database (~4GB), with 2 large tables (~3M records) having ~180K SELECTs/hour, ~2k UPDATEs/hour and ~1k INSERTs+DELETEs/hour. What would be the best practice to guarantee no locks for the reading tasks while inserting/updating/deleting? I was thinking about using a NOLOCK hint, but there is so much discussed about this (is good, is bad, it depends) that I'm a bit lost. I must say I've tried this in a dev environment and I didn't find any problems, but I don't want to put it on production until I get some feedback... Thank you! Luiggi

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  • Read large amount of data from file in Java

    - by Crozin
    Hello I've got text file that contains 1 000 002 numbers in following formation: 123 456 1 2 3 4 5 6 .... 999999 100000 Now I need to read that data and allocate it to int variables (the very first two numbers) and all the rest (1 000 000 numbers) to an array int[]. It's not a hard task, but - it's horrible slow. My first attempt was java.util.Scanner: Scanner stdin = new Scanner(new File("./path")); int n = stdin.nextInt(); int t = stdin.nextInt(); int array[] = new array[n]; for (int i = 0; i < n; i++) { array[i] = stdin.nextInt(); } It works as excepted but it takes about 7500 ms to execute. I need to fetch that data in up to several hundred of milliseconds. Then I tried java.io.BufferedReader: Using BufferedReader.readLine() and String.split() I got the same results in about 1700 ms, but it's still too many. How can I read that amount of data in less that 1 second? The final result should be equal to: int n = 123; int t = 456; int array[] = { 1, 2, 3, 4, ..., 999999, 100000 };

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  • How do I make "simple" throughput j2ee-filter?

    - by Tommy
    I'm looking to create a filter that can give me two things: number of request pr minute, and average responsetime pr minute. I already got the individual readings, I'm just not sure how to add them up. My filter captures every request, and it records the time each request takes: public void doFilter(ServletRequest request, ...() { long start = System.currentTimeMillis(); chain.doFilter(request, response); long stop = System.currentTimeMillis(); String time = Util.getTimeDifferenceInSec(start, stop); } This information will be used to create some pretty Google Chart charts. I don't want to store the data in any database. Just a way to get current numbers out when requested As this is a high volume application; low overhead is essential. I'm assuming my applicationserver doesn't provide this information.

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  • JAVA bytecode optimization

    - by Idob
    This is a basic question. I have code which shouldn't run on metadata beans. All metadata beans are located under metadata package. Now, I use reflection API to find out whether a class is located in the the metadata package. if (newEntity.getClass().getPackage().getName().contains("metadata")) I use this If in several places within this code. The question is: Should I do this once with: boolean isMetadata = false if (newEntity.getClass().getPackage().getName().contains("metadata")) { isMetadata = true; } C++ makes optimizations and knows that this code was already called and it won't call it again. Does JAVA makes optimization? I know reflection API is a beat heavy and I prefer not to lose expensive runtime.

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  • Why is my regex so much slower compiled than interpreted ?

    - by miket2e
    I have a large and complex C# regex that runs OK when interpreted, but is a bit slow. I'm trying to speed this up by setting RegexOptions.Compiled, and this seems to take about 30 seconds for the first time and instantly after that. I'm trying to negate this by compiling the regex to an assembly first, so my app can be as fast as possible. My problem is when the compiling delay takes place: Regex myComplexRegex = new Regex(regexText, RegexOptions.Compiled); MatchCollection matches = myComplexRegex.Matches(searchText); foreach (Match match in matches) // <--- when the one-time long delay kicks in { } This is making compiling to an assembly basically useless, as I still get the delay on the first foreach call. What I want is for all the compiling delay to be done in advance when I compile to the assembly, not when the user runs the app. Where am I going wrong ? (The code I'm using to compile to an assembly is similar to http://www.dijksterhuis.org/regular-expressions-advanced/ , if that's relevant ).

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