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  • Using FILE_FLAG_NO_BUFFERING will return noticeable speed gain?

    - by 9dan
    Recently noticed detail description of FILE_FLAG_NO_BUFFERING flag in MSDN, and read several Google search results about unbuffered I/O in Windows. http://msdn.microsoft.com/en-us/library/aa363858(v=vs.85).aspx I wondering now, is it really important to consider unbuffered option in file I/O programming? Because many programs use plain old C stream I/O or C++ iostream, I didn't gave any attention to FILE_FLAG_NO_BUFFERING flag before. Let's say we are developing photo explorer program like Picasa. If we implement unbuffered I/O, could thumbnail display speed show noticeable difference in ordinary users?

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  • Basic SQL Query, I am newbie

    - by user3530547
    I just started my database and query class on Monday. We met on Monday and just went over the syllabus, and on Wednesday the network at school was down so we couldn't even do the power point lecture. Right now I am working on my first homework assignment and I am almost finished but I am having trouble on one question. Here is is... Write a SELECT statement that returns one column from the Customers table named FullName that joins the LastName and FirstName columns. Format the columns with the last name, a comma, a space, and the first name like this: Doe, John Sort the result set by last name in ascending sequence. Return only the contacts whose last name begins with letters from M to Z. Here is what I have so far... USE md0577283 SELECT FirstName,LastName FROM Customers ORDER BY LastName,FirstName My question is how do I format is Lastname, FirstName like the professor wants and how do I only select names M-Z? If someone could point me in the right direction I would greatly appreciate it. Thank you. PS With all do respect, I didn't ask for the answer I asked for a nudge in the right direction so why the down vote guys?

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  • Does beginTransaction in Hibernate allocate a new DB connection?

    - by illscience
    Hi folks - Just wondering if beginning a new transaction in Hibernate actually allocates a connection to the DB? I'm concerned b/c our server begins a new transaction for each request received, even if that request doesn't interact with the DB. We're seeing DB connections as a major bottleneck, so I'm wondering if I should take the time narrow the scope of my transactions. Searched everywhere and haven't been able to find a good answer. The very simple code is here: SessionFactory sessionFactory = (SessionFactory) Context.getContext().getBean("sessionFactory"); sessionFactory.getCurrentSession().beginTransaction(); sessionFactory.getCurrentSession().setFlushMode(FlushMode.AUTO); thanks very much! a

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  • Exceptions handling in SQL?

    - by Vineet
    Is there any way to handle exceptions in sql(ORACLE 9i)? Since I was trying to divide values of a column that contains both numbers and literals ,I need to fetch out only numbers from it ,as if it divisible by any number then its number else if contains literals it would not get divided it will generate error. how to handle those errors? Please suggest!!

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  • mysql_fetch_row() not a valid result resource

    - by user1717305
    I am confused, I don't know what's wrong. I'm about to transfer all data from my first table to the other. Here is my code: $getdata = mysql_query("SELECT Quantity, Description, Total FROM ordercart"); while($row = mysql_fetch_row($getdata)) { foreach($row as $cell){ $query1 = mysql_query("INSERT INTO ordermem (Quantity, Description, Total) VALUES ($cell)",$connect); } mysql_free_result($getdata); } I get the error: Warning: mysql_fetch_row(): 5 is not a valid MySQL result resource.

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  • Find Consecutive Rows & Calculate Duration

    - by MannyKo
    I have a set a of data that tells me if a couple of systems are available or not every 5 or 15 minutes increments. For now, the time increment shouldn't matter. The data looks like this: Status Time System_ID T 10:00 S01 T 10:15 S01 F 10:30 S01 F 10:45 S01 F 11:00 S01 T 11:15 S01 T 11:30 S01 F 11:45 S01 F 12:00 S01 F 12:15 S01 T 12:30 S01 F 10:00 S02 F 10:15 S02 F 10:30 S02 F 10:45 S02 F 11:00 S02 T 11:15 S02 T 11:30 S02 I want to create a view that tells when a system is NOT available (i.e. when it is F), from what time, to what time, and duration which is to - from. Desired results: System_ID From To Duration S01 10:30 11:00 00:30 S01 11:45 12:15 00:30 S02 10:00 11:00 01:00 Here is the script data: DROP SCHEMA IF EXISTS Sys_data CASCADE; CREATE SCHEMA Sys_data; CREATE TABLE test_data ( status BOOLEAN, dTime TIME, sys_ID VARCHAR(10), PRIMARY KEY (dTime, sys_ID) ); INSERT INTO test_data (status, dTime, sys_ID) VALUES (TRUE, '10:00:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (TRUE, '10:15:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '10:30:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '10:45:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '11:00:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (TRUE, '11:15:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (TRUE, '11:30:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '11:45:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '12:00:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '12:15:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (TRUE, '12:30:00', 'S01'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '10:00:00', 'S02'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '10:15:00', 'S02'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '10:30:00', 'S02'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '10:45:00', 'S02'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (FALSE, '11:00:00', 'S02'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (TRUE, '11:15:00', 'S02'); INSERT INTO test_data (status, dTime, sys_ID) VALUES (TRUE, '11:30:00', 'S02'); Thank you in advance!

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  • Start all tab's activities for pre-cache

    - by Pentium10
    I have a TabActivity with three tabs defined. The first tab is light-weight and renders in acceptable time. But the 2nd and 3rd tab, does need a couple of seconds to get visually rendered, after I click them. I would like to launch them, after I've loaded my first tab, in background for pre-cache. Once they are loaded, I can switch quickly between them. So I am wondering how can I launch the 2nd and 3rd tab. They are intents loaded in the view area.

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  • MySQL: List rows who have one but not another many-to-many relationship

    - by Svish
    Not quite sure how to ask or define this, but can't figure it out. I have three tables like this: persons person_id, first_name, last_name hobbies hobby_id, name persons_hobbies person_id, hobby_id I need to make two lists. Persons that have both hobby A and B, and persons that have hobby A but not B. How can I write these two queries? Can't figure out how to do this with joining and all...

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  • Mysql multiple row count?

    - by Steven
    Hello, I have a database full of rows like id,action,date 2,2,2010-03-01 3,2,2010-03-01 4,3,2010-03-01 5,3,2010-03-01 6,4,2010-02-01 7,4,2010-02-01 And I want to select all the count all the 2's and all the 3's and all the 4's. But I don't want to have to do 3 different SELECT COUNT() commands, is there a way to do this in a single command? Note, I want to display this as something like Action 2 = 2 Action 3 = 2 Action 4 = 2 (etc etc). And I will also need to specific a date (so it only counts all the 2,3,4,etc for dates between 2010-02-03 and 2010-03-01 for example)

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  • Fastest way to read/store lots of multidimensional data? (Java)

    - by RemiX
    I have three questions about three nested loops: for (int x=0; x<400; x++) { for (int y=0; y<300; y++) { for (int z=0; z<400; z++) { // compute and store value } } } And I need to store all computed values. My standard approach would be to use a 3D-array: values[x][y][z] = 1; // test value but this turns out to be slow: it takes 192 ms to complete this loop, where a single int-assignment int value = 1; // test value takes only 66 ms. 1) Why is an array so relatively slow? 2) And why does it get even slower when I put this in the inner loop: values[z][y][x] = 1; // (notice x and z switched) This takes more than 4 seconds! 3) Most importantly: Can I use a data structure that is as quick as the assignment of a single integer, but can store as much data as the 3D-array?

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  • Merging some columns of two mysql tables where id = fileid

    - by garg
    There are two tables TableA filedata_id | user_id | filename 1 | 1 | file.txt 2 | 1 | file2.txt TableB a_id | date | filedataid | counter | state | cat_id | subcat_id | med_id 99 | 1242144 | 1 | 2 | v | 55 | 56 | 90 100 | 1231232 | 2 | 3 | i | 44 | 55 | 110 I want to move columns cat_id, subcat_id, med_id to TableA where tableA.filedata_id = TableB.filedataid The result should be: TableA filedata_id | user_id | filename | cat_id | subcat_id | med_id 1 | 1 | file.txt | 55 | 56 | 90 2 | 1 | file2.txt | 44 | 55 | 110 and so on. Is there a way to do this easily?

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  • SQL - Link to more table information

    - by BioXhazard
    I have a datagrid with 3 of 5 fields from a SQL table. The first databound was changed to an asp:hyperlink so the field can be clicked. What I want to do is, when the user clicks an object in the field, it sends the ID to another page. From there, it uses the request in order to display the required information which is found in the same SQL table. For example: User clicks on a cell in the first column, it brings them to a page with more information on that cell.

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  • fast load big object graph from DB

    - by Famos
    Hi I have my own data structure written in C# like: public class ElectricScheme { public List<Element> Elements { get; set; } public List<Net> Nets { get; set; } } public class Element { public string IdName { get; set; } public string Func { get; set; } public string Name { get; set; } public BaseElementType Type { get; set; } public List<Pin> Pins { get; set; } } public class Pin { public string IdName { get; set; } public string Name { get; set; } public BasePinType PinType { get; set; } public BasePinDirection PinDirection { get; set; } } public class Net { public string IdName { get; set; } public string Name { get; set; } public List<Tuple<Element,Pin>> ConnectionPoints { get; set; } } Where Elements count ~19000, each element contain =3 Pin, Nets count ~20000, each net contain =3 pair (Element, Pin) Parse txt (file size ~17mb) file takes 5 minutes. Serilization / Deserialization by default serializer ~3 minutes. Load from DB 20 minutes and not loaded... I use Entity Framework like public ElectricScheme LoadScheme(int schemeId) { var eScheme = (from s in container.ElectricSchemesSet where s.IdElectricScheme.Equals(schemeId) select s).FirstOrDefault(); if (eScheme == null) return null; container.LoadProperty(eScheme, "Elements"); container.LoadProperty(eScheme, "Nets"); container.LoadProperty(eScheme, "Elements.Pins"); return eScheme; } The problem is dependencies between Element and Pin... (for ~19000 elements ~95000 pins) Any ideas?

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  • which one is a faster/better sql practice?

    - by artsince
    Suppose I have a 2 column table (id, flag) and id is sequential. I expect this table to contain a lot of records. I want to periodically select the first row not flagged and update it. Some of the records on the way may have already been flagged, so I want to skip them. Does it make more sense if I store the last id I flagged and use it in my select statement, like select * from mytable where id > my_last_id order by id asc limit 1 or simply get the first unflagged row, like: select * from mytable where flagged = 'F' order by id asc limit 1 Thank you!

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  • MySQL, how to use returned data?

    - by aejo
    Well, I know there is a funciton mysql_fetch_array() and we can use it like this: while ($row = mysql_fetch_array($result)) { echo $row['name'] . "<br />"; } But is there any other way? For example, if there is only one element that can be returned, and not an array. Thanks)

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  • MySQL, select from different table... IF

    - by gubbfett
    I'm having a small trouble since it was a long time ago i studies databases and querys. For example i'll have two tables for cd:s, one with data and one with alternative translations. In the CD-table i have the original language, and it looks something like this Table for CDs (cds): id | name | language ----------------------- 1 | aaa | en 2 | bbb | en 3 | ccc | fi Table for languages (languages): cd_id | language | name ----------------------- 1 | fi | AAA 1 | de | AAACHTUNG 3 | en | CCC Now, i want to get all these cd:s in for example german, if there's no translation made i want it to be in the original language... How can i do this?

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  • mysql extra columns with same name from two tables

    - by salmane
    Table 1 has columns : entry_id user_id ... Table 2 has columns : entry_id user_id ... the user_id entry is not always the same so I would like to extract both of them so I can later on compare them in my script SELECT * FROM table1 as t1 INNER JOIN table2 as t2 on t1.entry_id=t2.entry_id WHERE t1.user_id='%s' I would like to extract t1.user_id and t2.user_id ...the problem is the result array has only user_id thank you

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  • Why is Python so slow?

    - by Riemannliness
    Why is Python such a slow language, on average, compared to C/C++? I learned Python as my first programming language, but I've only just started with C and already I can feel and see the difference.

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  • What's wrong with this inner query (MySQL)...

    - by stuboo
    ...besides the fact that I am a total amateur? My table is set up like this: CREATE TABLE `messages` ( `id` int(6) unsigned NOT NULL AUTO_INCREMENT, `patient_id` int(6) unsigned NOT NULL, `message` varchar(255) NOT NULL, `savedate` int(10) unsigned NOT NULL, `senddate` int(10) unsigned NOT NULL, `SmsSid` varchar(40) NOT NULL COMMENT 'where we store the cookies from twilio', `sendorder` tinyint(3) unsigned NOT NULL COMMENT 'the order we want the msg sent in', `sent` tinyint(1) NOT NULL COMMENT '0=queued, 1=sent, 2=sent-unqueued,4=rec-unread,5=recd-read', PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=143 ; I need a query that will SELECT * FROM `messages` WHERE `senddate` < $now AND `sent` = 0 (AND LIMIT TO ONLY ONE RECORD PER `patient_id`) I've tried the following: SELECT * FROM `messages` WHERE `senddate` IN (SELECT `patient_id`, max(`senddate`) GROUP by `patient_id`) AND `senddate` < $now AND `sent` = 0 ; But I get this error: MySQL client version: 5.1.37 `#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'GROUP by patient_id) AND senddate < 1270093898 AND sent = 0 LIMIT 0, 30' at line 5

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  • Sort MySQL query result by a alphanumeric field

    - by Jason Shultz
    I'm querying a table in a db using php. one of the fields is a column called "rank" and has data like the following: none 1-bronze 2-silver 3-gold ... 10-ambassador 11-president I want to be able to sort the results based on that "rank" column. any results where the field is "none" get excluded, so those don't factor in. As you can already guess, right now the results are coming back like this: 1-bronze 10-ambassador 11-president 2-silver 3-gold Of course, I would like for it to be sorted so it is like the following: 1-bronze 2-silver 3-gold ... 10-ambassador 11-president Right now the query is being returned as an object. I've tried different sort options like natsort, sort, array_multisort but haven't got it to work the way I'm sure it can. I would prefer keeping the results in an object form if possible. I'm passing the data on to a view in the next step. although, it's perfectly acceptable to pass the object to the view and then do the work there. so it's not an issue after all. :) thank you for your help. i'm hoping I'm making sense.

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  • Delete from empty table taking forver

    - by Will
    Hello, I have an empty table that previously had a large amount of rows. The table has about 10 columns and indexes on many of them, as well as indexes on multiple columns. DELETE FROM item WHERE 1=1 This takes approximately 40 seconds to complete SELECT * FROM item this takes 4 seconds. The execution plan of SELECT * FROM ITEM shows the following; SQL> select * from midas_item; no rows selected Elapsed: 00:00:04.29 Execution Plan ---------------------------------------------------------- 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=19 Card=123 Bytes=73 80) 1 0 TABLE ACCESS (FULL) OF 'MIDAS_ITEM' (Cost=19 Card=123 Byte s=7380) Statistics ---------------------------------------------------------- 0 recursive calls 0 db block gets 5263 consistent gets 5252 physical reads 0 redo size 1030 bytes sent via SQL*Net to client 372 bytes received via SQL*Net from client 1 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 0 rows processed any idea why these would be taking so long and how to fix it would be greatly appreciated!!

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  • Sorting MySQL table by next due date

    - by Zagga
    Hi folks, I have a MySQL table that stores (amongst other things) a persons date of birth. Is there any way to sort the table so the next due birthday is at the top? I have the date stored in standard yyyy-mm-dd DATE format and seperate year, month and day fields so I can sort it by the first birthday of the year (ORDER BY month, day) but I can't seem to get any further. Any help would be greatly appreciated. Zagga

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  • Outer select column value in joined subquery?

    - by Michael DePetrillo
    Is it possible to use a column value from an outer select within a joined subquery? SELECT table1.id, table2.cnt FROM table1 LEFT JOIN (SELECT COUNT(*) as `cnt` FROM table2 where table2.lt > table1.lt and table2.rt < table1.rt) as table2 ON 1; This results in "Unknown column 'table1.lt' in 'where clause'". Here is the db dump. CREATE TABLE IF NOT EXISTS `table1` ( `id` int(1) NOT NULL, `lt` int(1) NOT NULL, `rt` int(4) NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=latin1; CREATE TABLE IF NOT EXISTS `table2` ( `id` int(1) NOT NULL, `lt` int(1) NOT NULL, `rt` int(4) NOT NULL) ENGINE=MyISAM DEFAULT CHARSET=latin1; INSERT INTO `table1` (`id`, `lt`, `rt`) VALUES (1, 1, 4); INSERT INTO `table2` (`id`, `lt`, `rt`) VALUES (2, 2, 3);

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