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• How to query one table and add rows to another using that first query? MySQL

  - by Nickelbids

  Hello, I have some users setup in a MySQL table with different variables. I am trying to figure out what would be the best way to do this. Basically I want to award all of my registered and active users with bids which are stored in another table. So for the Table "users" I have ran this query: SELECT * FROM users WHERE active = 1 AND admin = 0 ORDER BY users.id ASC Which will show all active users who are not administrators. Now I would like to give each one of these users which are identified by the "ID" field in another table. So in the "bids" table I would need to add a new row for each one of those users with all of the same values except for the "user_id" field which will basically match the "id" field of the table "users" What would be the best approach for this. There are approximately 6,000+ users coming up in the first query. Please be gentle as I am not a programmer. Just need some friendly advice.

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• SQL query to select a range

  - by hansika attanayake

  I need to write an sql query (in c#) to select excel sheet data in "C" column starting from C19. But i cant specify the ending cell number because more data are getting added to the column. Hence i need to know how to specify the end of the column. Please help. I have mentioned the query that im using. I need to know what should be entered at the position of "C73"? OleDbCommand ccmd = new OleDbCommand(@"Select * From [SPAT$C19:C73]", conn);

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• Using temporary arrays to cut down on code - inefficient?

  - by tommaisey

  I'm new to c++ (and SO) so sorry if this is obvious. I've started using temporary arrays in my code to cut down on repetition and to make it easier to do the same thing to multiple objects. So instead of: MyObject obj1, obj2, obj3, obj4; obj1.doSomming(arg); obj2.doSomming(arg); obj3.doSomming(arg); obj4.doSomming(arg); I'm doing: MyObject obj1, obj2, obj3, obj4; MyObject* objs[] = {&obj1, &obj2, &obj3, &obj4}; for (int i = 0; i !=4; ++i) objs[i]->doSomming(arg); Is this detrimental to performance? Like, does it cause unnecessary memory allocation? Is it good practice? Thanks.

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• What can we do to make XML processing faster?

  - by adpd

  We work on an internal corporate system that has a web front-end as one of its interfaces. The front-end (Java + Tomcat + Apache) communicates to the back-end (proprietary system written in a COBOL-like language) through SOAP web services. As a result, we pass large XML files back and forth. We believe that this architecture has a significant impact on performance due to the large overhead of XML transportation and parsing. Unfortunately, we are stuck with this architecture. How can we make this XML set-up more efficient? Any tips or techniques are greatly appreciated.

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• join query with lowstock products with another table in magento

  - by muralikalpana

  I want to display some attributes in reports/products/lowstock grid. here how can i join another table with lowstock product id? here is the query /** @var $collection Mage_Reports_Model_Resource_Product_Lowstock_Collection */ $collection = Mage::getResourceModel('reports/product_lowstock_collection') ->addAttributeToSelect('*') ->setStoreId($storeId) ->filterByIsQtyProductTypes() ->joinInventoryItem('qty') ->joinInventoryItem('low_stock_date') ->useManageStockFilter($storeId) ->useNotifyStockQtyFilter($storeId) ->setOrder('qty', Varien_Data_Collection::SORT_ORDER_ASC); here i have to join with this productid with another table. i am not getting results if i use this query. $collection->getSelect()->join(array('t2' => 'lowstockorders'),'lowstock_inventory_item.product_id = t2.product_id','t2.product_id'); please anybody tell me how to join these tables thanks, murali

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• Which of these Array Initializations is better in Ruby?

  - by Bragaadeesh

  Hi, Which of these two forms of Array Initialization is better in Ruby? Method 1: DAYS_IN_A_WEEK = (0..6).to_a HOURS_IN_A_DAY = (0..23).to_a @data = Array.new(DAYS_IN_A_WEEK.size).map!{ Array.new(HOURS_IN_A_DAY.size) } DAYS_IN_A_WEEK.each do |day| HOURS_IN_A_DAY.each do |hour| @data[day][hour] = 'something' end end Method 2: DAYS_IN_A_WEEK = (0..6).to_a HOURS_IN_A_DAY = (0..23).to_a @data = {} DAYS_IN_A_WEEK.each do |day| HOURS_IN_A_DAY.each do |hour| @data[day] ||= {} @data[day][hour] = 'something' end end The difference between the first method and the second method is that the second one does not allocate memory initially. I feel the second one is a bit inferior when it comes to performance due to the numerous amount of Array copies that has to happen. However, it is not straight forward in Ruby to find what is happening. So, if someone can explain me which is better, it would be really great! Thanks

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• MySql query and table optimisation

  - by Cheeky

  Hi everyone. I am trying to run the following simple query on a table with 500K records. SELECT COUNT(*) AS impressionCount FROM impression WHERE 0 = 0 AND impressionObjectId1 = 'C69A54B8-B828-E2E4-2319A93011DF4120' AND impressionObjectId2 = '1'; This query is taking 10 seconds to run. I have tried creating individual indexes for the impressionObjectId1 and impressionObjectId2 columns, as well as a composite index using both. The composite worked well for a while, but now it is also slow. Here is my table structure: DROP TABLE IF EXISTS `impression`; CREATE TABLE `impression` ( `impressionId` varchar(50) NOT NULL, `impressionObjectId1` varchar(50) NOT NULL, `impressionObjectId2` varchar(50) default NULL, `impressionStampDate` datetime NOT NULL, PRIMARY KEY (`impressionId`), KEY `IX_object` (`impressionObjectId1`,`impressionObjectId2`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 ROW_FORMAT=DYNAMIC COMMENT='InnoDB free: 191488 kB'; Any advice would be greatly appreciated. Thanks EDIT: When adding an EXPLAIN, this is the output: 1, 'SIMPLE', 'impression', 'ref', 'IX_object', 'IX_object', '105', 'const,const', 304499, 'Using where; Using index'

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• Make SQL query more efficient

  - by Webnet

  I currently have this query which runs 2 of the exact same sub queries but pull different data. When I make the values comma separated it throws an SQL error saying the sub query can return only one value. Is there anything else I can do to avoid running multiple sub queries? SELECT product_id, ( SELECT COUNT(listing_id) FROM ebay_archive_product_listing_assoc WHERE product_id = product_master.product_id) as listing_count, sku, type_id, ( SELECT AVG(ebay_archive_listing.current_price), AVG(ebay_archive_listing.buy_it_now_price) FROM ebay_archive_listing WHERE id IN ( SELECT listing_id FROM ebay_archive_product_listing_assoc WHERE product_id = product_master.product_id ) AND ebay_archive_listing.start_time >= '.$startTimestamp.' AND ebay_archive_listing.start_time <= '.$endTimestamp.' AND ebay_archive_listing.current_price > 0 ) as average_bid_price, ( SELECT FROM ebay_archive_listing WHERE id IN ( SELECT listing_id FROM ebay_archive_product_listing_assoc WHERE product_id = product_master.product_id ) AND ebay_archive_listing.start_time >= '.$startTimestamp.' AND ebay_archive_listing.start_time <= '.$endTimestamp.' AND ebay_archive_listing.buy_it_now_price > 0 ) as average_buyout_price FROM product_master I'm aware of the syntax error... I'm selecting 2 seperate averages and am wondering if I can do it any simpler way.

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• Faster way of initializing arrays in Delphi

  - by Max

  I'm trying to squeeze every bit of performance in my Delphi application and now I came to a procedure which works with dynamic arrays. The slowest line in it is SetLength(Result, Len); which is used to initialize the dynamic array. When I look at the code for the SetLength procedure I see that it is far from optimal. The call sequence is as follows: _DynArraySetLength - DynArraySetLength DynArraySetLength gets the array length (which is zero for initialization) and then uses ReallocMem which is also unnecessary for initilization. I was doing SetLength to initialize dynamic array all the time. Maybe I'm missing something? Is there a faster way to do this?

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• How does Array.ForEach() compare to standard for loop in C#?

  - by DaveN59

  I pine for the days when, as a C programmer, I could type: memset( byte_array, '0xFF' ); and get a byte array filled with 'FF' characters. So, I have been looking for a replacement for this: for (int i=0; i < byteArray.Length; i++) { byteArray[i] = 0xFF; } Lately, I have been using some of the new C# features and have been using this approach instead: Array.ForEach<byte>(byteArray, b => b = 0xFF); Granted, the second approach seems cleaner and is easier on the eye, but how does the performance compare to using the first approach? Am I introducing needless overhead by using Linq and generics? Thanks, Dave

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• making mysql query using splite string?

  - by Marco

  lets say i have a group of number like (3,2,5) the normal way i use to split them and searching mysql to get value is to split them using explode in PHP EXAMPLE $string = '3,4,5'; $array = explode(',',$string); foreach($array as $value){ $query = 'SELECT ID FROM TABLE WHERE ID = "'.$value.'"'; } it work like this but it make the script extremely slow i need now if there is away to split this string into the query it self and return the result without looping with PHP ?

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• How to speed up a query?

  - by Soroush Khosravi

  I have a table that every request to the server, stores on it. For each request I will check that it is banned or not. For example it is a query: select * from requests where request_sessID = '4bc0331d983000902b4718c80f12e9b3' AND request_time > (UNIX_TIMESTAMP() - 3600) AND request_isEnable = 1 I also set the engine from InnoDB to MyISAM and row_format to Dynamic but nothing changed. My Hardware is very strong but it took about a minute to execute ! I am a programmer and newbie to mysql How can Speed Up this query? Thanks in Advance

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• where clause in linq query

  - by masoud

  in the below code "transmittalno.TransID" always has value but "doctranstocon.Transid" sometimes has value and sometimes does not, so when "doctranstocon.Transid" has value I have no problem but when there is not any value, when compare in the where clause like :"transmittalno.TransID == doctranstocon.Transid". It returns error" Object reference not set to an instance of an object." TranstoCons = from doctranstocon in _DocTranstoCons where ( transmittalno.TransID == doctranstocon.Transid ) select doctranstocon.tblTranstoCon I like TranstoCons returns null when there is not any value for " doctranstocon.Transid " How I can handle this error in the below linq query: var query = from transmittalno in _Transmittals Select new TransmittaltoConPresentationModel { TransID = transmittalno.TransID, Transmittal = transmittalno.TRANSMITTAL, TranstoCons = from doctranstocon in _DocTranstoCons where ( transmittalno.TransID == doctranstocon.Transid ) select doctranstocon.tblTranstoCon };

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• Query building depending checkboxes selection

  - by user3661845

  I want to build a query form my database depending my checkboxes list. My checkboxes: <input type="checkbox" id="searchName" checked> Name <input type="checkbox" id="searchAddress"> Address <input type="checkbox" id="searchCompany"> Company <input type="checkbox" id="searchComments"> Comments My PHP: $subQuery=''; if($_POST['searchName']=='true') { $subQuery .= " AND KDX_Name LIKE :KDX_SearchTerm"; } if($_POST['searchAddress']=='true') { $subQuery .= " OR KDX_PostalAddress LIKE :KDX_SearchTerm"; } if($_POST['searchCompany']=='true') { $subQuery .= " OR KDX_Company LIKE :KDX_SearchTerm"; } if($_POST['searchComments']=='true') { $subQuery .= " OR KDX_Comments LIKE :KDX_SearchTerm"; } My problem: If the first checkbox is not checked, my query is not working cause it works with OR whereas it must start with AND. Could you please help ? Thanks.

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• Small and fast .NET programs? - 65% runtime in ResolvePolicy

  - by forki23

  Hi, I tried to build a very very small .NET app in F#. It just has to convert a small string into another string and print the result to the console like: convert.exe myString == prints something like "myConvertedString" I used dottrace to analyze the performance: 26% (168ms) in my actual string conversion (I thinks this is ok.) 65,80% (425ms) in ResolvePolicy in System.Security.SecurityManager A runtime 500ms on every execution is way too slow. Can I do something to improve this? It would be Ok if only the first call needs this time. Regards, forki

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• How do I resolve "Unable to resolve attribute [organizationType.id] against path" exception?

  - by Dave

  I'm using Spring 3.1.1.RELEASE, Hibernate 4.1.0.Final, JUnit 4.8, and JPA 2.0 (hibernate-jpa-2.0-api). I'm trying to write a query and search based on fields of member fields. What I mean is I have this entity … @GenericGenerator(name = "uuid-strategy", strategy = "uuid.hex") @Entity @Table(name = "cb_organization", uniqueConstraints = {@UniqueConstraint(columnNames={"organization_id"})}) public class Organization implements Serializable { @Id @NotNull @GeneratedValue(generator = "uuid-strategy") @Column(name = "id") /* the database id of the Organization */ private String id; @ManyToOne @JoinColumn(name = "state_id", nullable = true, updatable = false) /* the State for the organization */ private State state; @ManyToOne @JoinColumn(name = "country_id", nullable = false, updatable = false) /* The country the Organization is in */ private Country country; @ManyToOne(optional = false) @JoinColumn(name = "organization_type_id", nullable = false, updatable = false) /* The type of the Organization */ private OrganizationType organizationType; Notice the members "organizationType," "state," and "country," which are all objects. I wish to build a query based on their id fields. This code @Override public List<Organization> findByOrgTypesCountryAndState(Set<String> organizationTypes, String countryId, String stateId) { CriteriaBuilder builder = entityManager.getCriteriaBuilder(); CriteriaQuery<Organization> criteria = builder.createQuery(Organization.class); Root<Organization> org = criteria.from(Organization.class); criteria.select(org).where(builder.and(org.get("organizationType.id").in(organizationTypes), builder.equal(org.get("state.id"), stateId), builder.equal(org.get("country.id"), countryId))); return entityManager.createQuery(criteria).getResultList(); } is throwing the exception below. How do I heal the pain? java.lang.IllegalArgumentException: Unable to resolve attribute [organizationType.id] against path at org.hibernate.ejb.criteria.path.AbstractPathImpl.unknownAttribute(AbstractPathImpl.java:116) at org.hibernate.ejb.criteria.path.AbstractPathImpl.locateAttribute(AbstractPathImpl.java:221) at org.hibernate.ejb.criteria.path.AbstractPathImpl.get(AbstractPathImpl.java:192) at org.mainco.subco.organization.repo.OrganizationDaoImpl.findByOrgTypesCountryAndState(OrganizationDaoImpl.java:248) at org.mainco.subco.organization.repo.OrganizationDaoTest.testFindByOrgTypesCountryAndState(OrganizationDaoTest.java:55) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20) at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74) at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83) at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184) at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71) at org.junit.runners.ParentRunner.run(ParentRunner.java:236) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

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• Retreiving multiple rows from a loop-created form... Stuck.

  - by hangston

  Hi All, Let me start by saying that I'm new to PHP, but I'm here to learn and would really appreciate your help. I use the following code to pull in data and create a form. This creates up to 40 lines for a user to fill out. Each line consists of the same information: Description, Amount, and Frequency. The remainder of the information needed is generated by the database. (See hidden fields) <?php $row = 0; do { $optid = $row_options['option_id']; echo "<tr>\n\t<td>" . htmlentities($row_options['option']) . "</td>\n"; echo "\t<td>" . "<input name='description' type='text' size='40' maxlength='120'/>" . "</td>\n"; echo "\t<td>" . "<input name='option_id' type='hidden' value='$optid' />$<input name='amount' type='text' size='10' maxlength='7'/>" . "</td>\n"; echo "\t<td>" . "<select name='assisted_frequency'> <option value='Monthly'>Monthly</option> <option value='Weekly'>Weekly</option> <option value='Daily'>Daily</option> <option value='Hourly'>Hourly</option> <option value='One-Time'>One-Time</option> </select>" . "</td>\n</tr>\n"; $array[$row] = array( $arraydesc[$row] = $_POST['description'], $arrayamto[$row] = $_POST['amount'], $arrayoptid[$row] = $optid, $arrayfreq[$row] = $_POST['frequency'], ); $row ++; } while ($row_options = mysql_fetch_assoc($options)); $counter = $row - 1; ?> I'm having troubles retrieving the information that the user inputs. My intent is to loop through each row after the user has input their information, then upload the mix of my database information and the user's information into another database. For example, the user would see, albeit prettier: form1 Option 1: description [input box] amount [input box] frequency [option box] Option 2: description [input box] amount [input box] frequency [option box] Option 3: description [input box] amount [input box] frequency [option box] Option 4: description [input box] amount [input box] frequency [option box] submit Upon submitting the form above, I'm using a query similar to the following to input the data into the database: for($row=0; $row<=$counter; $row++){ $insertSQL2 = sprintf("INSERT INTO table (option_id, amount, description, frequency) VALUES (%s, %s, %s, %s)", GetSQLValueString($arrayoptid[$row], "int"), GetSQLValueString($arrayamto[$row], "int"), GetSQLValueString($arraydesc[$row], "text"), GetSQLValueString($arrayfreq[$row], "text")); // code to submit query } I've tried for, foreach, arrays (what feels like the everything I know) to post each row (row by row) into the database. I either get just the last row of data, or no data at all. I also worry that the [$row] technique is adding characters to my data. What is the best way to retrieve each row of the user's inputs, then upload this data (row by row) into the database? Also, I would really appreciate your suggestions for improving my coding technique and the approach I'm taking. Thank you, Hangston

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• Retrieving multiple rows from a loop-created form... Stuck.

  - by hangston

  Let me start by saying that I'm new to PHP, but I'm here to learn and would really appreciate your help. I use the following code to pull in data and create a form. This creates up to 40 lines for a user to fill out. Each line consists of the same information: Description, Amount, and Frequency. The remainder of the information needed is generated by the database. (See hidden fields) <?php $row = 0; do { $optid = $row_options['option_id']; echo "<tr>\n\t<td>" . htmlentities($row_options['option']) . "</td>\n"; echo "\t<td>" . "<input name='description' type='text' size='40' maxlength='120'/>" . "</td>\n"; echo "\t<td>" . "<input name='option_id' type='hidden' value='$optid' />$<input name='amount' type='text' size='10' maxlength='7'/>" . "</td>\n"; echo "\t<td>" . "<select name='assisted_frequency'> <option value='Monthly'>Monthly</option> <option value='Weekly'>Weekly</option> <option value='Daily'>Daily</option> <option value='Hourly'>Hourly</option> <option value='One-Time'>One-Time</option> </select>" . "</td>\n</tr>\n"; $array[$row] = array( $arraydesc[$row] = $_POST['description'], $arrayamto[$row] = $_POST['amount'], $arrayoptid[$row] = $optid, $arrayfreq[$row] = $_POST['frequency'], ); $row ++; } while ($row_options = mysql_fetch_assoc($options)); $counter = $row - 1; ?> I'm having troubles retrieving the information that the user inputs. My intent is to loop through each row after the user has input their information, then upload the mix of my database information and the user's information into another database. For example, the user would see, albeit prettier: form1 Option 1: description [input box] amount [input box] frequency [option box] Option 2: description [input box] amount [input box] frequency [option box] Option 3: description [input box] amount [input box] frequency [option box] Option 4: description [input box] amount [input box] frequency [option box] submit Upon submitting the form above, I'm using a query similar to the following to input the data into the database: for($row=0; $row<=$counter; $row++){ $insertSQL2 = sprintf("INSERT INTO table (option_id, amount, description, frequency) VALUES (%s, %s, %s, %s)", GetSQLValueString($arrayoptid[$row], "int"), GetSQLValueString($arrayamto[$row], "int"), GetSQLValueString($arraydesc[$row], "text"), GetSQLValueString($arrayfreq[$row], "text")); // code to submit query } I've tried for, foreach, arrays (what feels like the everything I know) to post each row (row by row) into the database. I either get just the last row of data, or no data at all. I also worry that the [$row] technique is adding characters to my data. What is the best way to retrieve each row of the user's inputs, then upload this data (row by row) into the database? Also, I would really appreciate your suggestions for improving my coding technique and the approach I'm taking.

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• Quantifying the Performance of Garbage Collection vs. Explicit Memory Management

  - by EmbeddedProg

  I found this article here: Quantifying the Performance of Garbage Collection vs. Explicit Memory Management http://www.cs.umass.edu/~emery/pubs/gcvsmalloc.pdf In the conclusion section, it reads: Comparing runtime, space consumption, and virtual memory footprints over a range of benchmarks, we show that the runtime performance of the best-performing garbage collector is competitive with explicit memory management when given enough memory. In particular, when garbage collection has five times as much memory as required, its runtime performance matches or slightly exceeds that of explicit memory management. However, garbage collection’s performance degrades substantially when it must use smaller heaps. With three times as much memory, it runs 17% slower on average, and with twice as much memory, it runs 70% slower. Garbage collection also is more susceptible to paging when physical memory is scarce. In such conditions, all of the garbage collectors we examine here suffer order-of-magnitude performance penalties relative to explicit memory management. So, if my understanding is correct: if I have an app written in native C++ requiring 100 MB of memory, to achieve the same performance with a "managed" (i.e. garbage collector based) language (e.g. Java, C#), the app should require 5*100 MB = 500 MB? (And with 2*100 MB = 200 MB, the managed app would run 70% slower than the native app?) Do you know if current (i.e. latest Java VM's and .NET 4.0's) garbage collectors suffer the same problems described in the aforementioned article? Has the performance of modern garbage collectors improved? Thanks.

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• MySql - Get row number on select

  - by George

  Can I run a select statement and get the row number if the items are sorted? I have a table like this: mysql> describe orders; +-------------+---------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------------+------+-----+---------+----------------+ | orderID | bigint(20) unsigned | NO | PRI | NULL | auto_increment | | itemID | bigint(20) unsigned | NO | | NULL | | +-------------+---------------------+------+-----+---------+----------------+ I can then run this query to get the number of orders by ID: SELECT itemID, COUNT(*) as ordercount FROM orders GROUP BY itemID ORDER BY ordercount DESC; This gives me a count of each itemID in the table like this: +--------+------------+ | itemID | ordercount | +--------+------------+ | 388 | 3 | | 234 | 2 | | 3432 | 1 | | 693 | 1 | | 3459 | 1 | +--------+------------+ I want to get the row number as well, so I could tell that itemID 388 is the first row, 234 is second, etc (essentially the ranking of the orders, not just a raw count). I know I can do this in java when I get the result set back, but I was wondering if there was a way to handle it purely in SQL.

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• Removing non-alphanumeric characters in an Access Field.

  - by Jacques Tardie

  I need to remove hyphens from a string in a large number of access fields. What's the best way to go about doing this? Currently, the entries are follow this general format: 2010-54-1 2010-56-1 etc. I'm trying to run append queries off of this field, but I'm always getting validation errors causing the query to fail. I think the cause of this failure is the hypens in the entries, which is why I need to remove them. I've googled, and I see that there are a number of formatting guides using vbscript, but I'm not sure how I can integrate vb into Access. It's new to me :) Thanks in advance, Jacques

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• Persistance JDO - How to query a property of a collection with JDOQL?

  - by Sergio del Amo

  I want to build an application where a user identified by an email address can have several application accounts. Each account can have one o more users. I am trying to use the JDO Storage capabilities with Google App Engine Java. Here is my attempt: @PersistenceCapable @Inheritance(strategy = InheritanceStrategy.NEW_TABLE) public class AppAccount { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Long id; @Persistent private String companyName; @Persistent List<Invoices> invoices = new ArrayList<Invoices>(); @Persistent List<AppUser> users = new ArrayList<AppUser>(); // Getter Setters and Other Fields } @PersistenceCapable @EmbeddedOnly public class AppUser { @Persistent private String username; @Persistent private String firstName; @Persistent private String lastName; // Getter Setters and Other Fields } When a user logs in, I want to check how many accounts does he belongs to. If he belongs to more than one he will be presented with a dashboard where he can click which account he wants to load. This is my code to retrieve a list of app accounts where he is registered. public static List<AppAccount> getUserAppAccounts(String username) { PersistenceManager pm = JdoUtil.getPm(); Query q = pm.newQuery(AppAccount.class); q.setFilter("users.username == usernameParam"); q.declareParameters("String usernameParam"); return (List<AppAccount>) q.execute(username); } But I get the next error: SELECT FROM invoices.server.AppAccount WHERE users.username == usernameParam PARAMETERS String usernameParam: Encountered a variable expression that isn't part of a join. Maybe you're referencing a non-existent field of an embedded class. org.datanucleus.store.appengine.FatalNucleusUserException: SELECT FROM com.softamo.pelicamo.invoices.server.AppAccount WHERE users.username == usernameParam PARAMETERS String usernameParam: Encountered a variable expression that isn't part of a join. Maybe you're referencing a non-existent field of an embedded class. at org.datanucleus.store.appengine.query.DatastoreQuery.getJoinClassMetaData(DatastoreQuery.java:1154) at org.datanucleus.store.appengine.query.DatastoreQuery.addLeftPrimaryExpression(DatastoreQuery.java:1066) at org.datanucleus.store.appengine.query.DatastoreQuery.addExpression(DatastoreQuery.java:846) at org.datanucleus.store.appengine.query.DatastoreQuery.addFilters(DatastoreQuery.java:807) at org.datanucleus.store.appengine.query.DatastoreQuery.performExecute(DatastoreQuery.java:226) at org.datanucleus.store.appengine.query.JDOQLQuery.performExecute(JDOQLQuery.java:85) at org.datanucleus.store.query.Query.executeQuery(Query.java:1489) at org.datanucleus.store.query.Query.executeWithArray(Query.java:1371) at org.datanucleus.jdo.JDOQuery.execute(JDOQuery.java:243) at com.softamo.pelicamo.invoices.server.Store.getUserAppAccounts(Store.java:82) at com.softamo.pelicamo.invoices.test.server.StoreTest.testgetUserAppAccounts(StoreTest.java:39) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28) at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184) at org.junit.runners.ParentRunner.run(ParentRunner.java:236) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) Any idea? I am getting JDO persistance totally wrong?

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• DELETING doubled users (MySQL)

  - by vizzdoom

  Hi I have two tables. There are users informations from two sites: p_users p_users2 There are 3726 users in first and 13717 in second. Some users in p_users2 are in p_users. I want merge this two tables to the one big table - but rows with same usernames can't be doubled. How can I do this? I tried something like this: DELETE FROM p_users2 WHERE user_id IN ( select p.user_id from p_users p join p_users2 p2 on p.username=p2.username ) After that I should receive a table with unique usernames, which I want to export and import to the first one. But when I execute my query I got error: SQL Error (1093): You can't specify target table 'p_users2' for update in FROM clause. (MYSQL)

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• SQL Join to only the maximum row puzzle

  - by Billy ONeal

  Given the following example data: Users +--------------------------------------------------+ | ID | First Name | Last Name | Network Identifier | +--------------------------------------------------+ | 1 | Billy | O'Neal | bro4 | +----+------------+-----------+--------------------+ | 2 | John | Skeet | jsk1 | +----+------------+-----------+--------------------+ Hardware +----+-------------------+---------------+ | ID | Hardware Name | Serial Number | +----+-------------------+---------------+ | 1 | Latitude E6500 | 5555555 | +----+-------------------+---------------+ | 2 | Latitude E6200 | 2222222 | +----+-------------------+---------------+ HardwareAssignments +---------+-------------+-------------+ | User ID | Hardware ID | Assigned On | +---------+-------------+-------------+ | 1 | 1 | April 1 | +---------+-------------+-------------+ | 1 | 2 | April 10 | +---------+-------------+-------------+ | 2 | 2 | April 1 | +---------+-------------+-------------+ | 2 | 1 | April 11 | +---------+-------------+-------------+ I'd like to write a SQL query which would give the following result: +--------------------+------------+-----------+----------------+---------------+-------------+ | Network Identifier | First Name | Last Name | Hardware Name | Serial Number | Assigned On | +--------------------+------------+-----------+----------------+---------------+-------------+ | bro4 | Billy | O'Neal | Latitude E6200 | 2222222 | April 10 | +--------------------+------------+-----------+----------------+---------------+-------------+ | jsk1 | John | Skeet | Latitude E6500 | 5555555 | April 11 | +--------------------+------------+-----------+----------------+---------------+-------------+ My trouble is that the maximum "Assigned On" date for each user needs to be selected for each individual user and used for the actual join ... Is there a clever way accomplish this in SQL?

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• mySQL date range problem

  - by StealthRT

  Hey all i am in need of a little help with figuring out how to get a range of days for my select query. Here is the code i am trying out: select id, idNumber, theDateStart, theDateEnd from clients WHERE idNumber = '010203' AND theDateStart >= '2010-04-09' AND theDateEnd <= '2010-04-09'; This is what the data in the table looks like: TheDateStart = 2010-04-09 TheDateEnd = 2010-04-11 When testing that code above, it does not populate anything. If i take out the TheEndDate, it populates but with some other tables data as well which it should not do (it should only get one record). I know the problem is within the two date's. I'm not sure how to go about getting a date range for theDateStart and theDateEnd since if someone tries it, say, on 2010-04-10, it still needs to know its within rage of the 2010-04-09 - 2010-04-11. But right now, it does not... Any help would be great! :o) David

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