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  • Increase increment size to match GUID advantage

    - by TenaciousImpy
    Hi, I've been thinking of implementing this system, but can't help but feel there's a catch somewhere. One of the points of using GUID over incrementing int is that, in the future, if you were to merge databases together, you wouldn't have any clashes over the primary key/identifier. However, my approach is to set the increment size to X where X is the number of servers I'll most likely have in the future. Then, on each server, have the seed be an increment over the seed number on the previous server. That way, during merging, there would be no clashes with the primary key. Is this a safe, normal method or have I gone mental :)? Thanks

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  • Speeding up inner-joins and subqueries while restricting row size and table membership

    - by hiffy
    I'm developing an rss feed reader that uses a bayesian filter to filter out boring blog posts. The Stream table is meant to act as a FIFO buffer from which the webapp will consume 'entries'. I use it to store the temporary relationship between entries, users and bayesian filter classifications. After a user marks an entry as read, it will be added to the metadata table (so that a user isn't presented with material they have already read), and deleted from the stream table. Every three minutes, a background process will repopulate the Stream table with new entries (i.e. whenever the daemon adds new entries after the checks the rss feeds for updates). Problem: The query I came up with is hella slow. More importantly, the Stream table only needs to hold one hundred unread entries at a time; it'll reduce duplication, make processing faster and give me some flexibility with how I display the entries. The query (takes about 9 seconds on 3600 items with no indexes): insert into stream(entry_id, user_id) select entries.id, subscriptions_users.user_id from entries inner join subscriptions_users on subscriptions_users.subscription_id = entries.subscription_id where subscriptions_users.user_id = 1 and entries.id not in (select entry_id from metadata where metadata.user_id = 1) and entries.id not in (select entry_id from stream where user_id = 1); The query explained: insert into stream all of the entries from a user's subscription list (subscriptions_users) that the user has not read (i.e. do not exist in metadata) and which do not already exist in the stream. Attempted solution: adding limit 100 to the end speeds up the query considerably, but upon repeated executions will keep on adding a different set of 100 entries that do not already exist in the table (with each successful query taking longer and longer). This is close but not quite what I wanted to do. Does anyone have any advice (nosql?) or know a more efficient way of composing the query?

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  • date comparisons in Rails

    - by aressidi
    Hi there, I'm having trouble with a date comparison in a named scope. I'm trying to determine if an event is current based on its start and end date. Here's the named scope I'm using which kind of works, though not for events that have the same start and end date. named_scope :date_current, :conditions => ["Date(start_date) <= ? AND Date(end_date) >= ?", Time.now, Time.now] This returns the following record, though it should return two records, not one... >> Event.date_current => [#<Event id: 2161, start_date: "2010-02-15 00:00:00", end_date: "2010-02-21 00:00:00", ...] What it's not returning is this as well >> Event.find(:last) => #<Event id: 2671, start_date: "2010-02-16 00:00:00", end_date: "2010-02-16 00:00:00", ...> The server time seems to be in UTC and I presume that the entries are being stored in the DB in UTC. Any ideas as to what I'm doing wrong or what to try? Thanks!

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  • Correlate GROUP BY and LEFT JOIN on multiple criteria to show latest record?

    - by Sunbird
    In a simple stock management database, quantity of new stock is added and shipped until quantity reaches zero. Each stock movement is assigned a reference, only the latest reference is used. In the example provided, the latest references are never shown, the stock ID's 1,4 should have references charlie, foxtrot respectively, but instead show alpha, delta. How can a GROUP BY and LEFT JOIN on multiple criteria be correlated to show the latest record? http://sqlfiddle.com/#!2/6bf37/107 CREATE TABLE stock ( id tinyint PRIMARY KEY, quantity int, parent_id tinyint ); CREATE TABLE stock_reference ( id tinyint PRIMARY KEY, stock_id tinyint, stock_reference_type_id tinyint, reference varchar(50) ); CREATE TABLE stock_reference_type ( id tinyint PRIMARY KEY, name varchar(50) ); INSERT INTO stock VALUES (1, 10, 1), (2, -5, 1), (3, -5, 1), (4, 20, 4), (5, -10, 4), (6, -5, 4); INSERT INTO stock_reference VALUES (1, 1, 1, 'Alpha'), (2, 2, 1, 'Beta'), (3, 3, 1, 'Charlie'), (4, 4, 1, 'Delta'), (5, 5, 1, 'Echo'), (6, 6, 1, 'Foxtrot'); INSERT INTO stock_reference_type VALUES (1, 'Customer Reference'); SELECT stock.id, SUM(stock.quantity) as quantity, customer.reference FROM stock LEFT JOIN stock_reference AS customer ON stock.id = customer.stock_id AND stock_reference_type_id = 1 GROUP BY stock.parent_id

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  • Repository vs Data Access

    - by vdh_ant
    Hi guys In the context of the n-tier application, is there a difference between what you would consider your data access classes to be and your repositories? I tend to think yes but I just wanted to see what other thought. My thinking is that the job of the repository is just to contain and execute the raw query itself, where as the data access class would create the context, execute the repository (passing in the context), handle mapping the data model to the domain model and return the result back up... What do you guys think? Also do you see any of this changing in a Linq to XML scenario (assuming that you change the context for the relevant XDocument)? Cheers Anthony

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  • Date format error in vb.net ?

    - by ahmed
    I get this error when I run the application Incorrect syntax near 12, on debugging I found that this error is caused due to the # along with the date. Dim backdate as datetime backdate = DateTime.Now.AddDays(-1) on binding the data to the grid to filter the backdate records this error is caused Incorrect syntax near 12. myqry = " select SRNO,SUBJECT,ID where datesend =" backdate Now i am trying to extract only the date or shall I divide the date into day , month and year with DATEPART and take into a variable or convert the date or what should i do , Please help ???

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  • Error: A SQLParamenter wtih ParameterName @myparm is not contained by this SQLParameter Collection

    - by SidC
    Good Morning, I'm working on an ASP.NET 3.5 webforms application and have written the following code: Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click Dim connectionString As String = WebConfigurationManager.ConnectionStrings("Diel_inventoryConnectionString").ConnectionString Dim con As New SqlConnection(connectionString) Dim adapter1 As New SqlDataAdapter adapter1.SelectCommand = New SqlCommand adapter1.SelectCommand.CommandType = CommandType.StoredProcedure adapter1.SelectCommand.CommandText = "PartSproc" Dim parmNSN As New SqlParameter("@NSN", SqlDbType.NVarChar) Dim parmName As New SqlParameter("@PartName", SqlDbType.NVarChar) txtNSN.Text = adapter1.SelectCommand.Parameters("@NSN").Value txtSearch.Text = adapter1.SelectCommand.Parameters("@PartName").Value Dim dt As New DataTable() adapter1.Fill(dt) MySearch.DataSource = dt MySearch.DataBind() End Sub When I run the page, I receive the error A SQLParameter with @NSN is not contained by this SQLParameter Collection. I tried using apostrophes around the @NSN and @PartName but that does not work either and presents expression expected error. How might I rectify the above code so that it references the @NSN and @PartName parameters correctly? Thanks, Sid

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  • help with exception handling in linq

    - by stackoverflowuser
    I have the following code to retrieve customer name, total (orders ), sum (order details) for reach customer in Northwind database. The problem with below code is that it raises an exception since a few customers dont have any entry in orders table. I know using the query syntax (join) the exception can be avoided. I want to know if the same can be handled with the extension method syntax. CustomerOrderDataContext db = new CustomerOrderDataContext(); var customerOrders = db.Customers.Select(c => new { CompanyName = c.CompanyName, TotalOrders = c.Orders.Count(), TotalQuantity = c.Orders.SelectMany(o => o.Order_Details).Sum(o=>o.Quantity) });

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  • Compare and find differences in two tables in Oracle

    - by Ruslan
    Hi! i have 2 tables: account: ID, ACC, AE_CCY, DRCR_IND, AMOUNT, MODULE flex: ID, ACC, AE_CCY, DRCR_IND, AMOUNT, MODULE I want to show differences comparing only by: AE_CCY, DRCR_IND, AMOUNT, MODULE and ACC by first 4 characters Example: ID ACC AE_CCY DRCR_IND AMOUNT MODULE -- --------- ------ -------- ------ ------ 1 734647674 USD D 100 OP and in flex: ID ACC AE_CCY DRCR_IND AMOUNT MODULE -- --------- ------ -------- ------ ------ 1 734647654 USD D 100 OP 2 734665474 USD D 100 OP 9 734611111 USD D 100 OP ID's 2 and 9 should be shown as differences. If I use FULL JOIN I'll get no differences as substr(account.ACC,1,4) = substr(flex.ACC,1,4) are equal and others are equal and MINUS doesn't work because ID's different. Thanks.

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  • Select those objects whose related objects IDs are *all* in given string

    - by Jannis
    Hi Django people, I want to build a frontend to a recipe database which enables the user to search for a list of recipes which are cookable with the ingredients the user supplies. I have the following models class Ingredient(models.Model): name = models.CharField(max_length=100, unique=True) slug = models.SlugField(max_length=100, unique=True) importancy = models.PositiveSmallIntegerField(default=4) […] class Amount(models.Model): recipe = models.ForeignKey('Recipe') ingredient = models.ForeignKey(Ingredient) […] class Rezept(models.Model): name = models.CharField(max_length=100) slug = models.SlugField() instructions = models.TextField() ingredients = models.ManyToManyField(Ingredient, through=Amount) […] and a rawquery which does exactly what I want: It gets all the recipes whose required ingredients are all contained in the list of strings that the user supplies. If he supplies more than necessary, it's fine too. query = "SELECT *, COUNT(amount.zutat_id) AS selected_count_ingredients, (SELECT COUNT(*) FROM amount WHERE amount.recipe_id = amount.id) AS count_ingredients FROM amount LEFT OUTER JOIN amount ON (recipe.id = recipe.recipe_id) WHERE amount.ingredient_id IN (%s) GROUP BY amount.id HAVING count_ingredient=selected_count_ingredient" % ",".join([str(ingredient.id) for ingredient in ingredients]) rezepte = Rezept.objects.raw(query) Now, what I'm looking for is a way that does not rely on .raw() as I would like to do it purely with Django's queryset methods. Additionally, it would be awesome if you guys knew a way of including the ingredient's importancy in the lookup so that a recipe is still shown as a result even though one of its ingredients (that has an importancy of 0) is not supplied by the user.

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  • MySQL - are FK's useful / viable in a web app?

    - by yoda
    Hi all, I've encountered this discussion related to FK's and web applications. Basically some people say that FK's in web applications doesn't represent a real improvement and can even make the application slower in some cases. What do you guys think, what's your experience? -- A quote from Heikki Tuuri, creator of InnoDB engine, founder and CEO of Innobase: InnoDB checks foreign keys as soon as a row is updated, no batching is performed or checks delayed till transaction commit Foreign keys are often serious performance overhead, but help maintain data consistency Foreign Keys increase amount of row level locking done and can make it spread to a lot of tables besides the ones directly updated

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  • counting rows that date hasn't yet passed

    - by AdRock
    I am trying to count the number of rows whose date has not yet passed so i can get only the current records I get an error sayng MySQL error #111 Invalid use of group function SELECT COUNT(festivalid) FROM festivals WHERE min(datefrom) > now()

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  • Updating Excel Cell with Non-Numeric Data in C#

    - by kbo206
    I have a query that is ExcelQuery = "Update [Sheet1$] set CITIZEN_ID = #" + value + " where CITIZEN_ID = " + value; As you can see, I'm essentially just appending a "#" onto the CITIZEN_ID field. value is a int/numeric value. So if I had "256" in the CITIZEN_ID column it would be converted to "#256" When I execute this I get an OleDbException Syntax error in date in query expression so I surrounded part of the query in single quotes like this, ExcelQuery = "Update [Sheet1$] set CITIZEN_ID = '#" + value + "' where CITIZEN_ID = " + value; With that I get yet another OleDbException this time with, Data type mismatch in criteria expression. I'm guessing for some reason the CITIZEN_ID fields don't want to take anything besides a plain number. Is there any way I can remedy this to get that pound symbol in? Thanks!

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  • Get list of duplicate rows in MySql

    - by user347033
    Hi, i have a table like this ID nachname vorname 1 john doe 2 john doe 3 jim doe 4 Michael Knight I need a query that will return all the fields (select *) from the records that have the same nachname and vorname (in this case, records 1 and 2). Can anyone help me with this? Thanks

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  • Return order of MySQL SHOW COLUMNS

    - by rich
    Hey guys. Simple one this, but one I can't seem to find any information on so here goes. I need to find the columns in a specific table, which is no problem.... SHOW COLUMNS FROM tablename LIKE '%ColumnPrefix%'; But I need to know what order they will be returned, preferable by choosing to order the results ascending alphabetically. I have had no luck with using ORDER BY Field. Any ideas? Cheers!

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  • Entity Framework doesn't like 0..1 to * relationships.

    - by Orion Adrian
    I have a database framework where I have two tables. The first table has a single column that is an identity and primary key. The second table contains two columns. One is a nvarchar primary key and the other is a nullable foreign key to the first table. On the default import of the database I get the following error: Condition cannot be specified for Column member 'ForeignKeyId' because it is marked with a 'Computed' or 'Identity' StoreGeneratedPattern. where ForeignKeyId is the second foreign key reference in the second table. Is this just something the entity model doesn't do? Or am I missing something?

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  • MYSQL Convert rows to columns performance problem

    - by Tarski
    I am doing a query that converts rows to columns similar to this post but have encountered a performance problem. Here is the query:- SELECT Info.Customer, Answers.Answer, Answers.AnswerDescription, Details.Code1, Details.Code2, Details.Code3 FROM Info LEFT OUTER JOIN Answers ON Info.AnswerID = Answers.AnswerID LEFT OUTER JOIN (SELECT ReferenceNo, MAX(CASE DetailsIndicator WHEN 'cde1' THEN DetailsCode ELSE NULL END ) Code1, MAX(CASE DetailsIndicator WHEN 'cde2' THEN DetailsCode ELSE NULL END ) Code2, MAX(CASE DetailsIndicator WHEN 'cde3' THEN DetailsCode ELSE NULL END ) Code3 FROM DetailsData GROUP BY ReferenceNo) Details ON Info.ReferenceNo = Details.ReferenceNo There are less than 300 rows returned, but the Details table is about 180 thousand rows. The query takes 45 seconds to run and needs to take only a few seconds. When I type show processlist; into MYSQL it is hanging on "Sending Data". Any thoughts as to what the performance problem might be?

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  • Best Way to Generate Unique and consecutives numbers in Oracle

    - by RRUZ
    I need to generate unique and consecutive numbers (for use on an invoice), in a fast and reliable way. currently use a Oracle sequence, but in some cases generated numbers are not consecutive because of exceptions that may occur. I thought a couple of solutions to manage this problem, but neither of they convincing me. What solution do you recommend? Use a select max () SELECT MAX (NVL (doc_num, 0)) +1 FROM invoices Use a table to store the last number generated for the invoice. UPDATE docs_numbers SET last_invoice = last_invoice + 1 Another Solution?

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  • Why wont this sort in Solr work?

    - by Camran
    I need to sort on a date-field type, which name is "mod_date". It works like this in the browser adress-bar: http://localhost:8983/solr/select/?&q=bmw&sort=mod_date+desc But I am using a phpSolr client which sends an URL to Solr, and the url sent is this: fq=+category%3A%22Bilar%22+%2B+car_action%3AS%C3%A4ljes&version=1.2&wt=json&json.nl=map&q=%2A%3A%2A&start=0&rows=5&sort=mod_date+desc // This wont work and is echoed after this in php: $queryString = http_build_query($params, null, $this->_queryStringDelimiter); $queryString = preg_replace('/%5B(?:[0-9]|[1-9][0-9]+)%5D=/', '=', $queryString); This wont work, I dont know why! Everything else works fine, all right fields are returned. But the sort doesn't work. Any ideas? Thanks BTW: The field "mod_date" contains something like: 2010-03-04T19:37:22.5Z EDIT: First I use PHP to send this to a SolrPhpClient which is another php-file called service.php: require_once('../SolrPhpClient/Apache/Solr/Service.php'); $solr = new Apache_Solr_Service('localhost', 8983, '/solr/'); $results = $solr->search($querystring, $p, $limit, $solr_params); $solr_params is an array which contains the solr-parameters (q, fq, etc). Now, in service.php: $params['version'] = self::SOLR_VERSION; // common parameters in this interface $params['wt'] = self::SOLR_WRITER; $params['json.nl'] = $this->_namedListTreatment; $params['q'] = $query; $params['sort'] = 'mod_date desc'; // HERE IS THE SORT I HAVE PROBLEM WITH $params['start'] = $offset; $params['rows'] = $limit; $queryString = http_build_query($params, null, $this->_queryStringDelimiter); $queryString = preg_replace('/%5B(?:[0-9]|[1-9][0-9]+)%5D=/', '=', $queryString); if ($method == self::METHOD_GET) { return $this->_sendRawGet($this->_searchUrl . $this->_queryDelimiter . $queryString); } else if ($method == self::METHOD_POST) { return $this->_sendRawPost($this->_searchUrl, $queryString, FALSE, 'application/x-www-form-urlencoded'); } The $results contain the results from Solr... So this is the way I need to get to work (via php). This code below (also on top of this Q) works but thats because I paste it into the adress bar manually, not via the PHPclient. But thats just for debugging, I need to get it to work via the PHPclient: http://localhost:8983/solr/select/?&q=bmw&sort=mod_date+des // Not via phpclient, but works UPDATE (2010-03-08): I have tried Donovans codes (the urls) and they work fine. Now, I have noticed that it is one of the parameters causing the 'SORT' not to work. This parameter is the "wt" parameter. If we take the url from top of this Q, (fq=+category%3A%22Bilar%22+%2B+car_action%3AS%C3%A4ljes&version=1.2&wt=json&json.nl=map&q=%2A%3A%2A&start=0&rows=5&sort=mod_date+desc), and just simply remove the "wt" parameter, then the sort works. BUT the results appear differently, thus making my php code not able to recognize the results I believe. Donovan would know this I think. I am guessing in order for the PHPClient to work, the results must be in a specific structure, which gets messed up as soon as I remove the wt parameter. Donovan, help me please... Here is some background what I use your SolrPhpClient for: I have a classifieds website, which uses MySql. But for the searching I am using Solr to search some indexed fields. Then Solr returns an array of ID:numbers (for all matches of the search criteria). Then I use those ID:numbers to find everything in a MySql db and fetch all other information (example is not searchable information). So simplified: Search - Solr returns all matches in an array of ID:nrs - Id:numbers from Solr are the same as the Id numbers in the MySql db, so I can just make a simple match agains every record with the ID matching the ID from the Solr results array. I don't use Faceting, no boosting, no relevancy or other fancy stuff. I only sort by the latest classified put, and give the option to users to also sort on the cheapest price. Nothing more. Then I use the "fq" parameter to do queries on different fields in Solr depending on category chosen by users (example "cars" in this case which in my language is "Bilar"). I am really stuck with this problem here... Thanks for all help

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