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  • explain these select statements!

    - by user329820
    Hi, I can not get the difference betwwn these statements? would you please help me,I have read some sample of select statements but I did not get these ones. SELECT 'B' FROM T WHERE A = (SELECT NULL); SELECT 'C' FROM T WHERE A = ANY (SELECT NULL); SELECT 'D' FROM T WHERE A = A; I use MySQL

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  • SQL query - choosing 'last updated' record in a group, better db design?

    - by Jimmy
    Hi, Let's say I have a MySQL database with 3 tables: table 1: Persons, with 1 column ID (int) table 2: Newsletters, with 1 column ID (int) table 3: Subscriptions, with columns Person_ID (int), Newsletter_ID (int), Subscribed (bool), Updated (Datetime) Subscriptions.Person_ID points to a Person, and Subscription.Newsletter_ID points to a Newsletter. Thus, each person may have 0 or more subscriptions to 0 or more magazines at once. The table Subscriptions will also store the entire history of each person's subscriptions to each newsletter. If a particular Person_ID-Newsletter_ID pair doesn't have a row in the Subscriptions table, then it's equivalent to that pair having a subscription status of 'false'. Here is a sample dataset Persons ID 1 2 3 Newsletters ID 4 5 6 Subscriptions Person_ID Newsletter_ID Subscribed Updated 2 4 true 2010-05-01 3 4 true 2010-05-01 3 5 true 2010-05-10 3 4 false 2010-05-15 Thus, as of 2010-05-16, Person 1 has no subscription, Person 2 has a subscription to Newsletter 4, and Person 3 has a subscription to Newsletter 5. Person 3 had a subscription to Newsletter 4 for a while, but not anymore. I'm trying to do 2 kinds of query. A query that shows everyone's active subscriptions as of query time (we can assume that updated will never be in the future -- thus, this means returning the record with the latest 'updated' value for each Person_ID-Newsletter_ID pair, as long as Subscribed is true (if the latest record for a Person_ID-Newsletter_ID pair has a Subscribed status of false, then I don't want that record returned)). A query that returns all active subscriptions for a specific newsletter - same qualification as in 1. regarding records with 'false' in the Subscribed column. I don't use SQL/databases often enough to tell if this design is good, or if the SQL queries needed would be slow on a database with, say, 1M records in the Subscriptions table. I was using the Visual query builder tool in Visual Studio 2010 but I can't even get the query to return the latest updated record for each Person_ID-Newsletter_ID pair. Is it possible to come up with SQL queries that don't involve using subqueries (presumably because they would become too slow with a larger data set)? If not, would it be a better design to have a separate Subscriptions_History table, and every time a subscription status for a Person_ID-Newsletter-ID pair is added to Subscriptions, any existing record for that pair is moved to Subscriptions_History (that way the Subscriptions table only ever contains the latest status update for any Person_ID-Newsletter_ID pair)? I'm using .net on Windows, so would it be easier (or the same, or harder) to do this kind of queries using Linq? Entity Framework? Thanks!

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  • Import CSV to class structure as the user defines

    - by Assimilater
    I have a contact manager program and I would like to offer the feature to import csv files. The problem is that different data sources order the fields in different ways. I thought of programming an interface for the user to tell it the field order and how to handle exceptions. Here is an example line in one of many possible field orders: "ID#","Name","Rank","Address1","Address2","City","State","Country","Zip","Phone#","Email","Join Date","Sponsor ID","Sponsor Name" "Z1234","Call, Anson","STU","1234 E. 6578 S.","","Somecity","TX","United States","012345","000-000-0000","[email protected]","5/24/2010","z12343","Quantum Independence" Notice that in one data field "Name" there is a comma to separate last name and first name and in another there is not. My plan is to have a line for each field (ie ID, Name, City etc.) and a statement "import to" and list box with options like: Don't Import, BusinessJoin Date, First Name, Zip and the program recognizes those as properties of an object... I'd also like the user to be able to record preset field orders so they can re-use them for csv files from the same download source. Then I also need it to check if a record all ready exists (is there a record for Anson Call all ready?) and allow the user to tell it what to do if there is a record (ie mailing address may have changes, so if that field is filled overwrite it, or this mailing address is invalid, leave the current data untouched for this person, overwrite the rest). While I'm capable of coding this...i'm not very excited about it and I'm wondering if there's a tool or set of tools out there to all ready perform most of this functionality... I hope this makes sense...

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  • application specific seed data population

    - by user339108
    Env: JBoss, (h2, MySQl, postgres), JPA, Hibernate 3.3.x @Id @GeneratedValue(strategy = IDENTITY) private Integer key; Currently our primary keys are created using the above annotation. We expect to support a large number of users (~million users), what key should be used. Should it be Integer or Long or should I use the unsigned versions of the above declarations. We have a j2ee application which needs to be populated with some seed data on installation. On purchase, the customer creates his own data on top of the application. We just want to make sure that there is enough room to ship, modify or add data for future releases. What would be the best mechanism to support this, we had looked at starting all table identifiers from a certain id (say 1000) but this mandates modifying primary key generation to have table or sequence based generators and we have around ~100 tables. We are not sure if this is the right strategy for this. If we use a signed integer approach for the key, would it make sense to have the seed data as everything starting from 0 and below (i.e -ve numbers), so that all customer specific data will be available on 0 and above (i.e. +ve numbers)

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  • about Select statement !

    - by user329820
    hi, I have read that after select we use column-names but I have found a statement that was like this: SELECT 'A' FROM T WHERE A = NULL; would you lease help me? thanks (A is a column- name here?) my DBMS is MySQL

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  • Table index design

    - by Swoosh
    I would like to add index(s) to my table. I am looking for general ideas how to add more indexes to a table. Other than the PK clustered. I would like to know what to look for when I am doing this. So, my example: This table (let's call it TASK table) is going to be the biggest table of the whole application. Expecting millions records. IMPORTANT: massive bulk-insert is adding data in this table table has 27 columns: (so far, and counting :D ) int x 9 columns = id-s varchar x 10 columns bit x 2 columns datetime x 5 columns INT COLUMNS all of these are INT ID-s but from tables that are usually smaller than Task table (10-50 records max), example: Status table (with values like "open", "closed") or Priority table (with values like "important", "not so important", "normal") there is also a column like "parent-ID" (self - ID) join: all the "small" tables have PK, the usual way ... clustered STRING COLUMNS there is a (Company) column (string!) that is something like "5 characters long all the time" and every user will be restricted using this one. If in Task there are 15 different "Companies" the logged in user would only see one. So there's always a filter on this one. Might be a good idea to add an index to this column? DATE COLUMNS I think they don't index these ... right? Or can / should be?

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  • Dmbedded couchDB

    - by Chang
    CouchDB is great, I like its replication functionality, but it's a bit larger and slower when used in desktop application. As I tested in intel duo core cpu, 12 seconds to load 10000 docs 10 seconds to insert 10000 doc, but need 20 seconds to update view, so total is 30 seconds Is there any No SQL implementation which has the same replication functionality, but the size is very small, and the speed is quite good( 1 second to load 10000 docs). Thanks

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  • How to find specific row in MySQL query result?

    - by Šime Vidas
    So I do this to retrieve my entire table: $result = mysql_query( 'SELECT * FROM mytable' ); Then, in another part of my PHP-page, I do another query (for a specific row): $result2 = mysql_query( 'SELECT * FROM mytable WHERE id = ' . $id ); $row = mysql_fetch_array( $result2 ); So, I'm performing two querys. However, I don't really have to do that, do I? I mean, the row that I'm retrieving in my second query already is present in $result (the result of my first query), since it contains my entire table. Therefore, instead of doing the second query, I would like to extract the desired row from $result directly (while keeping $result itself in tact). How would I do that? OK, so this is how I've implemented it: function getRowById ( $result, $id ) { while ( $row = mysql_fetch_array( $result ) ) { if ( $row['id'] == $id ) { mysql_data_seek( $result, 0 ); return $row; } } }

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  • Zend Framework Relations vs. Table Select

    - by rtmilker
    Hey! I just want to know your guys opinion on using join tables within the zend framework. Of course you can use relations by defining a referenceMap and dependentTables and stuff, or using setIntegrityCheck(false) within a db select(). The setIntegrityCheck version seems a little bit dirty to me, but the other version is not very suitable for big querys and joining many tables... I'm a PHP developer for 5 years now and new to the zend framework and just want get a direction for my first project. Thanks!!!

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  • Facebook style messaging system schema design

    - by Jamie
    Hi all, I'm looking to implement a facebook style messaging system (thread messages) into a site of mine. Do you think this schema markup looks okay? Doctrine schema.yml: UserMessage: tableName: user_message actAs: [Timestampable] columns: id: { type: integer(10), primary: true, autoincrement: true } sender_id : { type: integer(10), notnull: true } sender_read: { type: boolean, default: 1 } subject: { type: string(255), notnull: true } message: { type: string(1000), notnull: true } hash: { type: string(32), notnull: true } relations: UserMessageRecipient as Recipient: type: many local: id foreign: message_id UserMessageReply as Reply: type: many local: id foreign: message_id UserMessageReply: tableName: user_message_reply columns: id: { type: integer(10), primary: true, autoincrement: true } user_message_id as message_id: { type: integer(10), notnull: true } message: { type: string(1000), notnull: true } sender_id: { type: integer(10), notnull: true } relations: UserMessage as Message: local: message_id foreign: id type: one UserMessageRecipient: tableName: user_message_recipient actAs: [Timestampable] columns: id: { type: integer(10), primary: true, autoincrement: true } user_message_id as message_id: { type: integer(10), notnull: true } recipient_id: { type: integer(10), notnull: true } recipient_read: { type: boolean, default: 0 } When I a new reply is made,i'll make sure the boolean for "recipient_read" for each recipient is set to false and of course i'll make sure sender_read is set to false too. I'm using a hash for the URL: http://example.com/user/messages/aadeb18f8bdaea49882ec4d2a8a3c062 (As the id will be starting from 1, i don't wish to have http://example.com/user/messages/1. Yeah, I could start incrementing from a bigger number, but i'd prefer to start at 1.) Is this a good way to go about it? Your thoughts and suggestions would be hugely appreciated. Thanks guys!

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  • How do i get the data from a surveillance camera to a storage i can stream from?

    - by radbyx
    Hi my sisters house was robbed chrismas evening :( I talked with her about making a surveillance system for her. The idea is to have a system that detects intruders and then send a SMS to you while streaming it to a private website. The hard part: How and where do I storage the data from the camera so it's streamable? I think i can manage to do the streaming, website and SMS server, but i need the data (fundamentation). Thanks, any help is much appriciated.

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  • DB Architecture : Linking to intersection or to main tables?

    - by Jean-Nicolas
    Hi, I'm creating fantasy football system on my website but i'm very confuse about how I should link some of my table. Tables The main table is Pool which have all the info about the ruling of the fantasy draft. A standard table User, which contains the usual stuff. Intersection table called pools_users which contains id,pool_id,user_id because a user could be in more than one pool, and a pool contains more than 1 user. The problem Table Selections = that's the table that is causing problem. That's the selection that the user choose for his pool. This is related to the Player table but thats not relevant for this problem. Should I link this table to the table Pools_users or should I link it with both main table Pool and User. This table contains id,pool_id,user_id,player_id,... What is the best way link my tables? When I want to retrieve my data, I normally want the information to be divided BY users. "This user have those selections, this one those selections, etc).

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  • Transaction within transaction

    - by user281521
    Hello, I want to know if open a transaction inside another is safe and encouraged? I have a method: def foo(): session.begin try: stuffs except Exception, e: session.rollback() raise e session.commit() and a method that calls the first one, inside a transaction: def bar(): stuffs try: foo() #<<<< there it is :) stuffs except Exception, e: session.rollback() raise e session.commit() if I get and exception on the foo method, all the operations will be rolled back? and everything else will work just fine? thanks!!

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  • Tablesorter - filter inside input fields and values

    - by Zeracoke
    I have a small quest to accomplish, and I reached a point when nothing works... So the problem is. I have a paged table with a lot of input fields inside the rows with values, and I would like to search inside these values. Let me Show this, I hope that somebody will got the idea what I should do... <script type="text/javascript"> // add parser through the tablesorter addParser method $.tablesorter.addParser({ id: 'inputs', is: function(s) { return false; }, format: function(s, table, cell, cellIndex) { var $c = $(cell); // return 1 for true, 2 for false, so true sorts before false if (!$c.hasClass('updateInput')) { $c .addClass('updateInput') .bind('keyup', function() { $(table).trigger('updateCell', [cell, false]); // false to prevent resort }); } return $c.find('input').val(); }, type: 'text' }); $(function() { $('table').tablesorter({ widgets: ['zebra', 'stickyHeaders', 'resizable', 'filter'], widgetOptions: { stickyHeaders : '', // number or jquery selector targeting the position:fixed element stickyHeaders_offset : 110, // added to table ID, if it exists stickyHeaders_cloneId : '-sticky', // trigger "resize" event on headers stickyHeaders_addResizeEvent : true, // if false and a caption exist, it won't be included in the sticky header stickyHeaders_includeCaption : true, // The zIndex of the stickyHeaders, allows the user to adjust this to their needs stickyHeaders_zIndex : 2, // jQuery selector or object to attach sticky header to stickyHeaders_attachTo : null, // scroll table top into view after filtering stickyHeaders_filteredToTop: true, resizable: true, filter_onlyAvail : 'filter-onlyAvail', filter_childRows : true, filter_startsWith : true, filter_useParsedData : true, filter_defaultAttrib : 'data-value' }, headers: { 1: {sorter: 'inputs', width: '50px'}, 2: {sorter: 'inputs'}, 3: {sorter: 'inputs'}, 4: {sorter: 'inputs'}, 5: {sorter: 'inputs'}, 6: {sorter: 'inputs'}, 7: {sorter: 'inputs', width: '100px'}, 8: {sorter: 'inputs', width: '140px'}, 9: {sorter: 'inputs'}, 10: {sorter: 'inputs'}, 11: {sorter: 'inputs'}, } }); $('table').tablesorterPager({container: $(".pager"), positionFixed: false, size: 50, pageDisplay : $(".pagedisplay"), pageSize : $(".pagesize"), }); $("#table1").tablesorter(options); /* make second table scroll within its wrapper */ options.widgetOptions.stickyHeaders_attachTo = '.wrapper'; // or $('.wrapper') $("#table2").tablesorter(options); }); </script> The structure of the tables: <tr class="odd" style="display: table-row;"> <form action="/self.php" method="POST"> </form><input type="hidden" name="f" value="data"> <td><input type="hidden" name="mod_id" value="741">741</td> <td class="updateInput"><input type="text" name="name" value="Test User Name"></td> <td class="updateInput"><input type="text" name="address" value="2548451 Random address"></td> <td class="updateInput"><input type="email" name="email" value=""></td> <td class="updateInput"><input type="text" name="entitlement" value="none"></td> <td class="updateInput"><input type="text" name="card_number" value="6846416548644352"></td> <td class="updateInput"><input type="checkbox" name="verify" value="1" checked=""></td> <td class="updateInput"><input type="checkbox" name="card_sended" value="1" checked=""></td> <td class="updateInput"><input type="text" name="create_date" value="2014-02-12 21:09:16"></td> <td class="updateInput"><a href="self.php?f=data&amp;del=741">X</a></td> <td class="updateInput"><input type="submit" value="SAVE"></td><td class="updateInput"></td></tr> So the thing is I don't know how to configure the filter to search these values... I already added some options, but none of them are working... Any help would be great!

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  • How to Auto-Increment Non-Primary Key? - SQL Server

    - by user311509
    CREATE TABLE SupplierQuote ( supplierQuoteID int identity (3504,2) CONSTRAINT supquoteid_pk PRIMARY KEY, PONumber int identity (9553,20) NOT NULL . . . CONSTRAINT ponumber_uq UNIQUE(PONumber) ); The above ddl produces an error: Msg 2744, Level 16, State 2, Line 1 Multiple identity columns specified for table 'SupplierQuote'. Only one identity column per table is allowed. How can i solve it? I want PONumber to be auto-incremented.

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  • need help with a simple SQL update statement.

    - by Tony
    There's a field with type of varchar. It actually stores a float point string. Like 2.0 , 12.0 , 34.5 , 67.50 ... What I need is a update statement that remove the ending zeros of fields like 2.0 , 12.0 , change them to their integer representation , that is 2 , 12 ...,and leave 3.45 , 67.50 unchanged . How should I do this ? I am using oracle 10.

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  • Better alternative to autonumber primary keys

    - by Comrad_Durandal
    I am looking for a better primary key than the autonumber data type, namely for the reason that it's limited to a long integer, when I really just need the field to reflect a number or text string that will never ever repeat, no matter HOW many records are added or deleted from the table. The problem is I am not sure how to implement something like turning the current date and time into a hexadecimal string and using that as a unique field I can use as a primary key. Am I just being too paranoid about running out of space?

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