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  • Strange error from mysql storage engine

    - by zerkms
    General error: 1030 Got error -1 from storage engine the used storage engine is innodb the query was runned when i got it today morning was: SELECT feeds.* FROM feeds ORDER BY RAND() LIMIT 1 i know rand() is bad but it's very small table (<500 records) and not loaded project this error i receive approximately once a day. cannot google anything relevant :-(

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  • Does MySQL short-circuit the ORDER BY clause?

    - by nickf
    Given this SQL: SELECT * FROM mytable ORDER BY mycolumn, RAND() Assuming that mycolumn happens to only contain unique values (and hence, contains enough information to perform the ORDER BY), does MySQL short-circuit the operation and skip evaluating the rest?

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  • retrieving deleted web pages

    - by vishnu
    I have recently published a web service to my site through visual studios ... I was so dumb to select delete existing files option ... Can anyone please help me out how do i get back my deleted files from the server...

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  • Access: strange results with queries against MDB file

    - by Craig Johnston
    I am running the following SQL against an MDB file, a copy of which is located here: http://hotfile.com/dl/40641614/2353dfc/test.mdb.html (perfectly clean file, no macros or viruses) SELECT datediff("d", MAX(invoice.date), Now) As Date_Diff , MAX(invoice.date) AS max_invoice_date , customer.number AS customer_number FROM invoice INNER JOIN customer ON invoice.customer_number = customer.number GROUP BY customer.number If the the following was added: HAVING datediff("d", MAX(invoice.date), Now) > 365 would this simply exclude rows with Date_Diff <= 365? What should be the effect of the HAVING clause here?

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  • MYSQL get the name from another table that is associated with the first table

    - by Juan Gonzales
    I can't figure out why this statement is not working SELECT myChurches.id AS id, myChurches.church_name AS church_name FROM myChurches INNER JOIN church_staff ON church_staff.church_id=myChurches.id WHERE church_staff.mem_id='$logOptions_id' ORDER BY myChurches.church_name ASC Basically I need to find the person's that are staff members of a church from one table and want to get the 'name' of that church FROM the 'myChurches' table. Hopefully that makes sense. Thanks in advance

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  • Many-To-Many Query with Linq-To-NHibernate

    - by rjygraham
    Ok guys (and gals), this one has been driving me nuts all night and I'm turning to your collective wisdom for help. I'm using Fluent Nhibernate and Linq-To-NHibernate as my data access story and I have the following simplified DB structure: CREATE TABLE [dbo].[Classes]( [Id] [bigint] IDENTITY(1,1) NOT NULL, [Name] [nvarchar](100) NOT NULL, [StartDate] [datetime2](7) NOT NULL, [EndDate] [datetime2](7) NOT NULL, CONSTRAINT [PK_Classes] PRIMARY KEY CLUSTERED ( [Id] ASC ) CREATE TABLE [dbo].[Sections]( [Id] [bigint] IDENTITY(1,1) NOT NULL, [ClassId] [bigint] NOT NULL, [InternalCode] [varchar](10) NOT NULL, CONSTRAINT [PK_Sections] PRIMARY KEY CLUSTERED ( [Id] ASC ) CREATE TABLE [dbo].[SectionStudents]( [SectionId] [bigint] NOT NULL, [UserId] [uniqueidentifier] NOT NULL, CONSTRAINT [PK_SectionStudents] PRIMARY KEY CLUSTERED ( [SectionId] ASC, [UserId] ASC ) CREATE TABLE [dbo].[aspnet_Users]( [ApplicationId] [uniqueidentifier] NOT NULL, [UserId] [uniqueidentifier] NOT NULL, [UserName] [nvarchar](256) NOT NULL, [LoweredUserName] [nvarchar](256) NOT NULL, [MobileAlias] [nvarchar](16) NULL, [IsAnonymous] [bit] NOT NULL, [LastActivityDate] [datetime] NOT NULL, PRIMARY KEY NONCLUSTERED ( [UserId] ASC ) I omitted the foreign keys for brevity, but essentially this boils down to: A Class can have many Sections. A Section can belong to only 1 Class but can have many Students. A Student (aspnet_Users) can belong to many Sections. I've setup the corresponding Model classes and Fluent NHibernate Mapping classes, all that is working fine. Here's where I'm getting stuck. I need to write a query which will return the sections a student is enrolled in based on the student's UserId and the dates of the class. Here's what I've tried so far: 1. var sections = (from s in this.Session.Linq<Sections>() where s.Class.StartDate <= DateTime.UtcNow && s.Class.EndDate > DateTime.UtcNow && s.Students.First(f => f.UserId == userId) != null select s); 2. var sections = (from s in this.Session.Linq<Sections>() where s.Class.StartDate <= DateTime.UtcNow && s.Class.EndDate > DateTime.UtcNow && s.Students.Where(w => w.UserId == userId).FirstOrDefault().Id == userId select s); Obviously, 2 above will fail miserably if there are no students matching userId for classes the current date between it's start and end dates...but I just wanted to try. The filters for the Class StartDate and EndDate work fine, but the many-to-many relation with Students is proving to be difficult. Everytime I try running the query I get an ArgumentNullException with the message: Value cannot be null. Parameter name: session I've considered going down the path of making the SectionStudents relation a Model class with a reference to Section and a reference to Student instead of a many-to-many. I'd like to avoid that if I can, and I'm not even sure it would work that way. Thanks in advance to anyone who can help. Ryan

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  • How can I use linq to initialize an array of repeated elements?

    - by Eric
    At present, I'm using something like this to build a list of 10 objects: myList = (from _ in Enumerable.Range(0, 9) select new MyObject {...}).toList() This is based off my python background, where I'd write: myList = [MyObject(...) for _ in range(10)] Note that I want my list to contain 10 instances of my object, not the same instance 10 times. Is this still a sensible way to do things in C#? Is there a cost to doing it this way over a simple for loop?

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  • LINQ entity query performance

    - by Abdel Olakara
    Hi all, I have a silly question. I would like to know if there is performance deference in these two quries: var cObject = from cust in entities.Customer where cust.id == cid select cust; and var cObject = entities.Customer.First( c=> c.id == cid); My query return only one record as I am querying with the primary key. But do they make any difference?

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  • how can we check file types before uploading them in asp.net?

    - by LostLord
    how can we check file types (formats such as jpg) without using file extensions before -uploading them- in asp.net with c# ? i am using vs 2008 + asp.net + c# + TELERIK Controls (RadUpload) ========================================================================================= imagine that some body change the text file extension to jpg and select it in a upload conrol such as radupload ... how can we recognize that this file is truely jpg or not?

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  • Trying to understand the usage of class_eval

    - by eMxyzptlk
    Hello everyone, I'm using the rails-settings gem, and I'm trying to understand how you add functions to ActiveRecord classes (I'm building my own library for card games), and I noticed that this gem uses one of the Meta-programming techniques to add the function to the ActiveRecord::Base class (I'm far from Meta-programming master in ruby, but I'm trying to learn it) module RailsSettings class Railtie < Rails::Railtie initializer 'rails_settings.initialize', :after => :after_initialize do Railtie.extend_active_record end end class Railtie def self.extend_active_record ActiveRecord::Base.class_eval do def self.has_settings class_eval do def settings RailsSettings::ScopedSettings.for_thing(self) end scope :with_settings, :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :select => "DISTINCT #{self.table_name}.*" scope :with_settings_for, lambda { |var| { :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'" } } scope :without_settings, :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :conditions => 'settings.id IS NULL' scope :without_settings_for, lambda { |var| { :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'", :conditions => 'settings.id IS NULL' } } end end end end end end What I don't understand is why he uses class_eval on ActiveRecord::Base, wasn't it easier if he just open the ActiveRecord::Base class and define the functions? Specially that there's nothing dynamic in the block (What I mean by dynamic is when you do class_eval or instance_eval on a string containing variables) something like this: module ActiveRecord class Base def self.has_settings class_eval do def settings RailsSettings::ScopedSettings.for_thing(self) end scope :with_settings, :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :select => "DISTINCT #{self.table_name}.*" scope :with_settings_for, lambda { |var| { :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'" } } scope :without_settings, :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :conditions => 'settings.id IS NULL' scope :without_settings_for, lambda { |var| { :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'", :conditions => 'settings.id IS NULL' } } end end end end I understand the second class_eval (before the def settings) is to define functions on the fly on every class that 'has_settings' right ? Same question here, I think he could use "def self.settings" instead of "class_eval.... def settings", no ?

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  • Converting a certain SQL query into relational algebra

    - by Fumler
    Just doing an assignment for my database course and I just want to double check that I've correctly wrapped my head around relational algebra. The SQL query: SELECT dato, SUM(pris*antall) AS total FROM produkt, ordre WHERE ordre.varenr = produkt.varenr GROUP BY dato HAVING total >= 10000 The relational algebra: stotal >= 10000( ?R(dato, total)( sordre.varenr = produkt.varenr( datoISUM(pris*antall(produkt x ordre)))) Is this the correct way of doing it?

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  • Using Frameset with Treeviews in ASP.Net

    - by Ben
    Afternoon, I am trying have an HTML file containing a frameset which contains two frames. I have populated the left Frame with a URL containing a TreeView with URL's for the nodes. I would like the to be able to select a URL from the treeview in the left hand frame, and have it set the src of the right hand frame to be that URL. Is that possible? Thanks

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  • Get selected value of dropdownlist in asp.net MVC

    - by Xulfee
    how can i get select value of dropdownlist and here is my code which is working fine. var list = new[] { new Person { Id = 1, Name = "Name1" }, new Person { Id = 2, Name = "Name2" }, new Person { Id = 3, Name = "Name3" } }; var selectList = new SelectList(list, "Id", "Name", 2); ViewData["People"] = selectList; <%= Html.DropDownListFor(model => model.Peoples, ViewData["People"] as IEnumerable<SelectListItem>)%>

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  • How to get a Clean String in Javascript?

    - by streetparade
    i have a long String. With some German characters and lots of new lines tabs ect.. In a Selectbox user can select a text, on change i do document.getElementById('text').value=this.value; But this fails. I just get a "unterminated string literal" as error in JavaScript. I think i should clean the string. How can i do it in JavaScript?

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  • displaying the values in textbox based on AJAX fetched entries

    - by Anurag
    hello, I've a table in which addition rows can be generatred as per the user need by clicking a javascript function. Each row has a drop down list, and based on the values of this an AJAX script fetchs some values which has to be displayed in corresponding textfields of the same row.. here is the code for HTML.. <td><div align="center"> <label> <select name="gcno1" id="gcno1" onchange="fetch_gc(this)"> <option value="0">NIL</option> <option value="2">1</option> <?php while($row=mysql_fetch_array($result)) { ?> <option value="<?php echo $row[0]; ?>"><?php echo $row[0]; ?></option> <?php }?> </select> </label> </div></td> <td><div align="center"><input name="date1" id="date1" type="text" size="10" /> </div></td> and here is the AJAX which I'm writing... xmlhttp = new XMLHttpRequest(); var value=encodeURIComponent(document.getElementById('gcno1').value); var parameters="param1="+value; xmlhttp.open("POST", 'fetch_gc.php', true); xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); xmlhttp.send(parameters); xmlhttp.onreadystatechange=function(){ if(xmlhttp.readyState == 4 && xmlhttp.status == 200) { var detail=xmlhttp.responseText.split('+'); alert(detail[0]); document.getElementsByName('date1').value=String(detail[0]); alert("life " + document.getElementById('gcno1').value); } } The alert inside the AJAX shows the correct response text, detail[0] but is unable to put the value in corresponding textbox i.e. with name 'gcno1'...... Please help me with this problem...

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  • Mysterious constraints problem with SQL Server 2000

    - by Ramon
    Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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  • Wordpress - Total User Count who only have posts

    - by knightrider
    I want to display total number of user who only have posts at Wordpress. I can get all users by this query <?php $user_count = $wpdb->get_var("SELECT COUNT(*) FROM $wpdb->users;"); echo $user_count ?> But for the user count only with posts, i think i might need to join another table, does anyone have snippets ? Thanks.

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  • XQuery performance in SQL Server

    - by Carl Hörberg
    Why does this quite simple xquery takes 10min to execute in sql server (the 2mb xml document stored in one column) compared to 14 seconds when using oxygen/file based querying? SELECT model.query('declare default element namespace "http://www.sbml.org/sbml/level2"; for $all_species in //species, $all_reactions in //reaction where data($all_species/@compartment)="plasma_membrane" and $all_reactions/listOfReactants/speciesReference/@species=$all_species/@id return <result>{data($all_species/@id)}</result>') from sbml;

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  • Advanced SQL query with lots of joins

    - by lund.mikkel
    Hey fellow programmers Okay, first let me say that this is a hard one. I know the presentation may be a little long. But I how you'll bare with me and help me through anyway :D So I'm developing on an advanced search for bicycles. I've got a lot of tables I need to join to find all, let's say, red and brown bikes. One bike may come in more then one color! I've made this query for now: SELECT DISTINCT p.products_id, #simple product id products_name, #product name products_attributes_id, #color id pov.products_options_values_name #color name FROM products p LEFT JOIN products_description pd ON p.products_id = pd.products_id INNER JOIN products_attributes pa ON pa.products_id = p.products_id LEFT JOIN products_options_values pov ON pov.products_options_values_id = pa.options_values_id LEFT JOIN products_options_search pos ON pov.products_options_values_id = pos.products_options_values_id WHERE pos.products_options_search_id = 4 #code for red OR pos.products_options_search_id = 5 #code for brown My first concern is the many joins. The Products table mainly holds product id and it's image and the Products Description table holds more descriptive info such as name (and product ID of course). I then have the Products Options Values table which holds all the colors and their IDs. Products Options Search is containing the color IDs along with a color group ID (products_options_search_id). Red has the color group code 4 (brown is 5). The products and colors have a many-to-many relationship managed inside Products Attributes. So my question is first of all: Is it okay to make so many joins? Is i hurting the performance? Second: If a bike comes in both red and brown, it'll show up twice even though I use SELECT DISTINCT. Think this is because of the INNER JOIN. Is this possible to avoid and do I have to remove the doubles in my PHP code? Third: Bikes can be double colored (i.e. black and blue). This means that there are two rows for that bike. One where it says the color is black and one where is says its blue. (See second question). But if I replace the OR in the WHERE clause it removes both rows, because none of them fulfill the conditions - only the product. What is the workaround for that? I really hope you will and can help me. I'm a little desperate right now :D Regards Mikkel Lund

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