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• ASP.Net MVC Interview Questions and Answers

  - by Samir R. Bhogayta

  About ASP.Net MVC The ASP.Net MVC is the framework provided by Microsoft that lets you develop the applications that follows the principles of Model-View-Controller (MVC) design pattern. The .Net programmers new to MVC thinks that it is similar to WebForms Model (Normal ASP.Net), but it is far different from the WebForms programming.  This article will tell you how to quick learn the basics of MVC along with some frequently asked interview questions and answers on ASP.Net MVC 1. What is ASP.Net MVC The ASP.Net MVC is the framework provided by Microsoft to achieve     separation of concerns that leads to easy maintainability of the     application. Model is supposed to handle data related activity View deals with user interface related work Controller is meant for managing the application flow by communicating between Model and View. Normal 0 false false false EN-US X-NONE X-NONE 2. Why to use ASP.Net MVC The strength of MVC (i.e. ASP.Net MVC) listed below will answer this question MVC reduces the dependency between the components; this makes your code more testable. MVC does not recommend use of server controls, hence the processing time required to generate HTML response is drastically reduced. The integration of java script libraries like jQuery, Microsoft MVC becomes easy as compared to Webforms approach. 3. What do you mean by Razor The Razor is the new View engine introduced in MVC 3.0. The View engine is responsible for processing the view files [e.g. .aspx, .cshtml] in order to generate HTML response. The previous versions of MVC were dependent on ASPX view engine.  4. Can we use ASPX view engine in latest versions of MVC Yes. The Recommended way is to prefer Razor View 5. What are the benefits of Razor View?      The syntax for server side code is simplified      The length of code is drastically reduced      Razor syntax is easy to learn and reduces the complexity Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} 6. What is the extension of Razor View file? .cshtml (for c#) and .vbhtml (for vb) 7. How to create a Controller in MVC Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} Create a simple class and extend it from Controller class. The bare minimum requirement for a class to become a controller is to inherit it from ControllerBase is the class that is required to inherit to create the controller but Controller class inherits from ControllerBase. 8. How to create an Action method in MVC Add a simple method inside a controller class with ActionResult return type. 9. How to access a view on the server    The browser generates the request in which the information like Controller name, Action Name and Parameters are provided, when server receives this URL it resolves the Name of Controller and Action, after that it calls the specified action with provided parameters. Action normally does some processing and returns the ViewResult by specifying the view name (blank name searches according to naming conventions).   10. What is the default Form method (i.e. GET, POST) for an action method GET. To change this you can add an action level attribute e.g [HttpPost] Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} 11. What is a Filter in MVC? When user (browser) sends a request to server an action method of a controller gets invoked; sometimes you may require executing a custom code before or after action method gets invoked, this custom code is called as Filter. 12. What are the different types of Filters in MVC? a. Authorization filter b. Action filter c. Result filter d. Exception filter [Do not forget the order mentioned above as filters gets executed as per above mentioned sequence] 13. Explain the use of Filter with an example? Suppose you are working on a MVC application where URL is sent in an encrypted format instead of a plain text, once encrypted URL is received by server it will ignore action parameters because of URL encryption. To solve this issue you can create global action filter by overriding OnActionExecuting method of controller class, in this you can extract the action parameters from the encrypted URL and these parameters can be set on filterContext to send plain text parameters to the actions.     14. What is a HTML helper? A HTML helper is a method that returns string; return string usually is the HTML tag. The standard HTML helpers (e.g. Html.BeginForm(),Html.TextBox()) available in MVC are lightweight as it does not rely on event model or view state as that of in ASP.Net server controls.

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• Data that has been deleted in P6, how is it updated in Analytics

  - by Jeffrey McDaniel

  In P6 Reporting Database 2.0 the ETL process looked to the refrdel table in the P6 PMDB to determine which projects were deleted. The refrdel table could not be cleared out between ETL runs or those deletes would be lost. After the ETL process is run the refrdel can be cleared out. It is important to keep any purging of the refrdel in a consistent cycle so the ETL process can pick up these deletes and process them accordingly.  In P6 Reporting Database 2.2 and higher the Extended Schema is used as the data source. In the Extended Schema, deleted data is filtered out by the views. The Extended Schema services will handle any interaction with the refrdel table, this concern with timing refrdel cleanup and ETL runs is not applicable as of this release. In the Extended Schema tables (ex. TaskX) there can still be deleted data present. The Extended Schema views join on the primary PMDB tables (ex. Task) and filter out any deleted data.  Any data that was deleted that remains in the Extended Schema tables can be cleaned out at a designated time by running the clean up procedure as documented in the P6 Extended Schema white paper. This can be run occasionally but is not necessary to run often unless large amounts of data has been deleted.

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• Parallelize incremental processing in Tabular #ssas #tabular

  - by Marco Russo (SQLBI)

  I recently came in a problem trying to improve the parallelism of Tabular processing. As you know, multiple tables can be processed in parallel, whereas the processing of several partitions within the same table cannot be parallelized. When you perform an incremental update by adding only new rows to existing table, what you really do is adding rows to a partition, so adding rows to many tables means adding rows to several partitions. The particular condition you have in this case is that every partition in which you add rows belongs to a different table. Adding rows implies using the ProcessAdd command; its QueryBinding parameter specifies a SQL syntax to read new rows, otherwise the original query specified for the partition will be used, and it could generate duplicated data if you don’t have a dynamic behavior on the SQL side. If you create the required XMLA code manually, you will find that the QueryBinding node that should be part of the ProcessAdd command has to be moved out from ProcessAdd in case you are using a Batch command with more than one Process command (which is the reason why you want to use a single batch: run multiple process operations in parallel!). If you use AMO (Analysis Management Objects) you will find that this combination is not supported, even if you don’t have a syntax error compiling the code, but you might obtain this error at execution time: The syntax for the 'Process' command is incorrect. The 'Bindings' keyword cannot appear under a 'Process' command if the 'Process' command is a part of a 'Batch' command and there are more than one 'Process' commands in the 'Batch' or the 'Batch' command contains any out of line related information. In this case, the 'Bindings' keyword should be a part of the 'Batch' command only. If this is happening to you, the best solution I’ve found is manipulating the XMLA code generated by AMO moving the Binding nodes in the right place. A more detailed description of the issue and the code required to send a correct XMLA batch to Analysis Services is available in my article Parallelize ProcessAdd with AMO. By the way, the same technique (and code) can be used also if you have the same problem in a Multidimensional model.

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• Android Card Game Database for Deck Building

  - by Singularity222

  I am making a card game for Android where a player can choose from a selection of cards to build a deck that would contain around 60 cards. Currently, I have the entire database of cards created that the user can browse. The next step is allowing the user to select cards and create a deck with whatever cards they would like. I have a form where the user can search for specific cards based off a few different attributes. The search results are displayed in a List Activity. My thought about deck creation is to add the primary key of each card the user selects to a SQLite Database table with the amount they would like in the deck. This way as the user performs searches for cards they can see the state of the deck. Once the user decides to save the deck. I'll export the card list to XML and wipe the contents of the table. If the user wanted to make changes to the deck, they would load it, it would be parsed back into the table so they could make the changes. A similar situation would occur when the eventually load the deck to play a game. I'm just curious what the rest of you may think of this method. Currently, this is a personal project and I am the only one working on it. If I can figure out the best implementation before I even begin coding I'm hoping to save myself some time and trouble.

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• Optimize Many-to-Many with SUMMARIZE and Other Techniques

  - by Marco Russo (SQLBI)

  We are still in the early days of DAX and even if I have been using it since 2 years ago, there is still a lot to learn on that. One of the topics that historically interests me (and many of the readers here, probably) is the many-to-many relationships between dimensions in a dimensional data model. When I and Alberto wrote the The Many to Many Revolution 2.0 we discovered the SUMMARIZE based pattern very late in the whitepaper writing. It is very important for performance optimization and it should be always used. In the last month, Gerhard Brueckl also presented an approach based on cross table filtering behavior that simplify the syntax involved, even if it’s harder to explain how it works internally. I published a short article titled Optimize Many-to-Many Calculation in DAX with SUMMARIZE and Cross Table Filtering on SQLBI website just to provide a quick reference to the three patterns available. A further study is still required to compare performance between SUMMARIZE and Cross Table Filtering patterns. Up to now, I haven’t observed big differences between them, even if their execution plans might be not identical and this suggest me that depending on other conditions you might favor one over the other.

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• Object pools for efficient resource management

  - by GameDevEnthusiast

  How can I avoid using default new() to create each object? My previous demo had very unpleasant framerate hiccups during dynamic memory allocations (usually, when arrays are resized), and creating lots of small objects which often contain one pointer to some DirectX resource seems like an awful lot of waste. I'm thinking about: Creating a master look-up table to refer to objects by handles (for safety & ease of serialization), much like EntityList in source engine Creating a templated object pool, which will store items contiguously (more cache-friendly, fast iteration, etc.) and the stored elements will be accessed (by external systems) via the global lookup table. The object pool will use the swap-with-last trick for fast removal (it will invoke the object's ~destructor first) and will update the corresponding indices in the global table accordingly (when growing/shrinking/moving elements). The elements will be copied via plain memcpy(). Is it a good idea? Will it be safe to store objects of non-POD types (e.g. pointers, vtable) in such containers? Related post: Dynamic Memory Allocation and Memory Management

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• Maximum Length Of IP Address: 15 (IPv4) & 39(IPv6)

  - by Gopinath

  Problem You are designing a database table for a web application that requires to store IP address of users who visits the site. The IP address is required to be stored a character data in the table. To define size of the character column you need to know maximum length of IP address. So, what is the maximum length of an IP address? Solution The IPv4 version of IP address is in the following format 255.255.255.255 To store IPv4 address we require 15 characters. The IPv6 version of IP address is grouped into sets of 4 hex digits separated by colons, like the below 2001:0db8:85a3:0000:0000:8a2e:0370:7334 To store IPv6 address you require a 39 characters long column. Conclusion As IPv4 and IPv6 are the commonly use protocols, you better define a column with 39 characters length so that both the format address are saved in to the table without any issues. This article titled,Maximum Length Of IP Address: 15 (IPv4) & 39(IPv6), was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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• Create MSDB Folders Through Code

  You can create package folders through SSMS, but you may also wish to do this as part of a deployment process or installation. In this case you will want programmatic method for managing folders, so how can this be done? The short answer is, go and look at the table msdb.dbo. sysdtspackagefolders90. This where folder information is stored, using a simple parent and child hierarchy format. To add new folder directly we just insert into the table - INSERT INTO dbo.sysdtspackagefolders90 ( folderid ,parentfolderid ,foldername) VALUES ( NEWID() -- New GUID for our new folder ,<<Parent Folder GUID>> -- Lookup the parent folder GUID if a child or another folder, or use the root GUID 00000000-0000-0000-0000-000000000000 ,<<Folder Name>>) -- New folder name There are also some stored procedures - sp_dts_addfolder sp_dts_deletefolder sp_dts_getfolder sp_dts_listfolders sp_dts_renamefolder To add a new folder to the root we could call the sp_dts_addfolder to stored procedure - EXEC msdb.dbo.sp_dts_addfolder @parentfolderid = '00000000-0000-0000-0000-000000000000' -- Root GUID ,@name = 'New Folder Name The stored procedures wrap very simple SQL statements, but provide a level of security, as they check the role membership of the user, and do not require permissions to perform direct table modifications.

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• Formatting a disk for Macintosh using Linux

  - by Ken Bloom

  I've been asked to move data from an old external hard drive to a new one, and to make the new one compatible with the Macintosh. (The old drive's USB connection has died, and I'm connecting to old the drive using a PC card that provieds an eSATA to the drive. The recipient's Macintosh doesn't have a PC card slot, so she can't access the old drive anymore. Hence, the new drive.) Naturally, I'm doing this data transfer using Linux. I've discovered that I can format the drive as HFS+ using mkfs.hfsplus from the hfsprogs package. But I need to know: do I need to do anything special with the partition table? Is there a special Macintosh partition table format that I need to format this disk to? If so, what tools can I use to get the right format for the partition table?

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• How does MySQL 5.5 and InnoDB on Linux use RAM?

  - by Loren

  Does MySQL 5.5 InnoDB keep indexes in memory and tables on disk? Does it ever do it's own in-memory caching of part or whole tables? Or does it completely rely on the OS page cache (I'm guessing that it does since Facebook's SSD cache that was built for MySQL was done at the OS-level: https://github.com/facebook/flashcache/)? Does Linux by default use all of the available RAM for the page cache? So if RAM size exceeds table size + memory used by processes, then when MySQL server starts and reads the whole table for the first time it will be from disk, and from that point on the whole table is in RAM? So using Alchemy Database (SQL on top of Redis, everything always in RAM: http://code.google.com/p/alchemydatabase/) shouldn't be much faster than MySQL, given the same size RAM and database?

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• Is this an acceptable approach to undo/redo in Python?

  - by Codemonkey

  I'm making an application (wxPython) to process some data from Excel documents. I want the user to be able to undo and redo actions, even gigantic actions like processing the contents of 10 000 cells simultaneously. I Googled the topic, and all the solutions I could find involves a lot of black magic or is overly complicated. Here is how I imagine my simple undo/redo scheme. I write two classes - one called ActionStack and an abstract one called Action. Every "undoable" operation must be a subclass of Action and define the methods do and undo. The Action subclass is passed the instance of the "document", or data model, and is responsible for committing the operation and remembering how to undo the change. Now, every document is associated with an instance of the ActionStack. The ActionStack maintains a stack of actions (surprise!). Every time actions are undone and new actions are performed, all undone actions are removed for ever. The ActionStack will also automatically remove the oldest Action when the stack reaches the configurable maximum amount. I imagine the workflow would produce code looking something like this: class TableDocument(object): def __init__(self, table): self.table = table self.action_stack = ActionStack(history_limit=50) # ... def delete_cells(self, cells): self.action_stack.push( DeleteAction(self, cells) ) def add_column(self, index, name=''): self.action_stack.push( AddColumnAction(self, index, name) ) # ... def undo(self, count=1): self.action_stack.undo(count) def redo(self, count=1): self.action_stack.redo(count) Given that none of the methods I've found are this simple, I thought I'd get the experts' opinion before I go ahead with this plan. More specifically, what I'm wondering about is - are there any glaring holes in this plan that I'm not seeing?

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• Joomla Secondary Users

  - by Gaz_Edge

  Background I have a joomla based application. My customers sign up and they register as a user on the site. My customers (primary customers) then have their own space on the site that they can then setup their own customers (secondary customer). Question/Problem The problem I am having is that I need to tag each secondary customer to a primary customer. I thought about just creating a new component and having a separate table that includes all the secondary customers. The problem is that I then lose out on all the authentication, session handling and login/logout that the core joomla _users component offers. I then thought about just having all the users in the core _users table and add the primary customer associated with each secondary customer to a field in a profile plugin. This would work for the most part, but this means that primary customers cannot create a secondary customer with a user name that already exists in the _users table. I didn't think this would be an issue, but several of my primary customers (currently only test users) have been confused by the site telling them a username is not available, since they can only see the names of their own secondary customers. Any ideas on some architectural changes I could make to solve this?

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• How to create a database in Oracle8 Lite with Developer 2000 ?

  - by Tareq

  Hi all, I am new in Oracle. I install Oracle 8 Lite with Developer 2000. Now I want to create a database for me. For that I open Oracle8 Navigator and Create a database which user is system. But in Oracle SQL*Plus I can not communicate with the database. Or even after creating a table using Oracle8 Navigator I can't alter the table. Please tell me how can I alter my table?

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• Thematic map contd.

  - by jsharma

  The previous post (creating a thematic map) described the use of an advanced style (color ranged-bucket style). The bucket style definition object has an attribute ('classification') which specifies the data classification scheme to use. It's values can be one of {'equal', 'quantile', 'logarithmic', 'custom'}. We use logarithmic in the previous example. Here we'll describe how to use a custom algorithm for classification. Specifically the Jenks Natural Breaks algorithm. We'll use the Javascript implementation in geostats.js The sample code above needs a few changes which are listed below. Include the geostats.js file after or before including oraclemapsv2.js <script src="geostats.js"></script> Modify the bucket style definition to use custom classification Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}    bucketStyleDef = {       numClasses : colorSeries[colorName].classes,       classification: 'custom', //'logarithmic',  // use a logarithmic scale       algorithm: jenksFromGeostats,       styles: theStyles,       gradient:  useGradient? 'linear' : 'off'     }; The function, which implements the custom classification scheme, is specified as the algorithm attribute value. It must accept two input parameters, an array of OM.feature and the name of the feature attribute (e.g. TOTPOP) to use in the classification, and must return an array of buckets (i.e. an array of or OM.style.Bucket  or OM.style.RangedBucket in this case). However the algorithm also needs to know the number of classes (i.e. the number of buckets to create). So we use a global to pass that info in. (Note: This bug/oversight will be fixed and the custom algorithm will be passed 3 parameters: the features array, attribute name, and number of classes). So createBucketColorStyle() has the following changes Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} var numClasses ; function createBucketColorStyle( colorName, colorSeries, rangeName, useGradient) {    var theBucketStyle;    var bucketStyleDef;    var theStyles = [];    //var numClasses ; numClasses = colorSeries[colorName].classes; ... and the function jenksFromGeostats is defined as Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} function jenksFromGeostats(featureArray, columnName) {    var items = [] ; // array of attribute values to be classified    $.each(featureArray, function(i, feature) {         items.push(parseFloat(feature.getAttributeValue(columnName)));    });    // create the geostats object    var theSeries = new geostats(items);    // call getJenks which returns an array of bounds    var theClasses = theSeries.getJenks(numClasses);    if(theClasses)    {     theClasses[theClasses.length-1]=parseFloat(theClasses[theClasses.length-1])+1;    }    else    {     alert(' empty result from getJenks');    }    var theBuckets = [], aBucket=null ;    for(var k=0; k<numClasses; k++)    {             aBucket = new OM.style.RangedBucket(             {low:parseFloat(theClasses[k]),               high:parseFloat(theClasses[k+1])             });             theBuckets.push(aBucket);     }     return theBuckets; } A screenshot of the resulting map with 5 classes is shown below. It is also possible to simply create the buckets and supply them when defining the Bucket style instead of specifying the function (algorithm). In that case the bucket style definition object would be    bucketStyleDef = {      numClasses : colorSeries[colorName].classes,      classification: 'custom',        buckets: theBuckets, //since we are supplying all the buckets      styles: theStyles,      gradient:  useGradient? 'linear' : 'off'    };

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• Database Migration Scripts: Getting from place A to place B

  - by Phil Factor

  We’ll be looking at a typical database ‘migration’ script which uses an unusual technique to migrate existing ‘de-normalised’ data into a more correct form. So, the book-distribution business that uses the PUBS database has gradually grown organically, and has slipped into ‘de-normalisation’ habits. What’s this? A new column with a list of tags or ‘types’ assigned to books. Because books aren’t really in just one category, someone has ‘cured’ the mismatch between the database and the business requirements. This is fine, but it is now proving difficult for their new website that allows searches by tags. Any request for history book really has to look in the entire list of associated tags rather than the ‘Type’ field that only keeps the primary tag. We have other problems. The TypleList column has duplicates in there which will be affecting the reporting, and there is the danger of mis-spellings getting there. The reporting system can’t be persuaded to do reports based on the tags and the Database developers are complaining about the unCoddly things going on in their database. In your version of PUBS, this extra column doesn’t exist, so we’ve added it and put in 10,000 titles using SQL Data Generator. /* So how do we refactor this database? firstly, we create a table of all the tags. */IF  OBJECT_ID('TagName') IS NULL OR OBJECT_ID('TagTitle') IS NULL  BEGIN  CREATE TABLE  TagName (TagName_ID INT IDENTITY(1,1) PRIMARY KEY ,     Tag VARCHAR(20) NOT NULL UNIQUE)  /* ...and we insert into it all the tags from the list (remembering to take out any leading spaces */  INSERT INTO TagName (Tag)     SELECT DISTINCT LTRIM(x.y.value('.', 'Varchar(80)')) AS [Tag]     FROM     (SELECT  Title_ID,          CONVERT(XML, '<list><i>' + REPLACE(TypeList, ',', '</i><i>') + '</i></list>')          AS XMLkeywords          FROM   dbo.titles)g    CROSS APPLY XMLkeywords.nodes('/list/i/text()') AS x ( y )  /* we can then use this table to provide a table that relates tags to articles */  CREATE TABLE TagTitle   (TagTitle_ID INT IDENTITY(1, 1),   [title_id] [dbo].[tid] NOT NULL REFERENCES titles (Title_ID),   TagName_ID INT NOT NULL REFERENCES TagName (Tagname_ID)   CONSTRAINT [PK_TagTitle]       PRIMARY KEY CLUSTERED ([title_id] ASC, TagName_ID)       ON [PRIMARY])        CREATE NONCLUSTERED INDEX idxTagName_ID  ON  TagTitle (TagName_ID)  INCLUDE (TagTitle_ID,title_id)        /* ...and it is easy to fill this with the tags for each title ... */        INSERT INTO TagTitle (Title_ID, TagName_ID)    SELECT DISTINCT Title_ID, TagName_ID      FROM        (SELECT  Title_ID,          CONVERT(XML, '<list><i>' + REPLACE(TypeList, ',', '</i><i>') + '</i></list>')          AS XMLkeywords          FROM   dbo.titles)g    CROSS APPLY XMLkeywords.nodes('/list/i/text()') AS x ( y )    INNER JOIN TagName ON TagName.Tag=LTRIM(x.y.value('.', 'Varchar(80)'))    END    /* That's all there was to it. Now we can select all titles that have the military tag, just to try things out */SELECT Title FROM titles  INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID  INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE tagname.tag='Military'/* and see the top ten most popular tags for titles */SELECT Tag, COUNT(*) FROM titles  INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID  INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  GROUP BY Tag ORDER BY COUNT(*) DESC/* and if you still want your list of tags for each title, then here they are */SELECT title_ID, title, STUFF(  (SELECT ','+tagname.tag FROM titles thisTitle    INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID    INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE ThisTitle.title_id=titles.title_ID  FOR XML PATH(''), TYPE).value('.', 'varchar(max)')  ,1,1,'')    FROM titles  ORDER BY title_ID So we’ve refactored our PUBS database without pain. We’ve even put in a check to prevent it being re-run once the new tables are created. Here is the diagram of the new tag relationship We’ve done both the DDL to create the tables and their associated components, and the DML to put the data in them. I could have also included the script to remove the de-normalised TypeList column, but I’d do a whole lot of tests first before doing that. Yes, I’ve left out the assertion tests too, which should check the edge cases and make sure the result is what you’d expect. One thing I can’t quite figure out is how to deal with an ordered list using this simple XML-based technique. We can ensure that, if we have to produce a list of tags, we can get the primary ‘type’ to be first in the list, but what if the entire order is significant? Thank goodness it isn’t in this case. If it were, we might have to revisit a string-splitter function that returns the ordinal position of each component in the sequence. You’ll see immediately that we can create a synchronisation script for deployment from a comparison tool such as SQL Compare, to change the schema (DDL). On the other hand, no tool could do the DML to stuff the data into the new table, since there is no way that any tool will be able to work out where the data should go. We used some pretty hairy code to deal with a slightly untypical problem. We would have to do this migration by hand, and it has to go into source control as a batch. If most of your database changes are to be deployed by an automated process, then there must be a way of over-riding this part of the data synchronisation process to do this part of the process taking the part of the script that fills the tables, Checking that the tables have not already been filled, and executing it as part of the transaction. Of course, you might prefer the approach I’ve taken with the script of creating the tables in the same batch as the data conversion process, and then using the presence of the tables to prevent the script from being re-run. The problem with scripting a refactoring change to a database is that it has to work both ways. If we install the new system and then have to rollback the changes, several books may have been added, or had their tags changed, in the meantime. Yes, you have to script any rollback! These have to be mercilessly tested, and put in source control just in case of the rollback of a deployment after it has been in place for any length of time. I’ve shown you how to do this with the part of the script .. /* and if you still want your list of tags for each title, then here they are */SELECT title_ID, title, STUFF(  (SELECT ','+tagname.tag FROM titles thisTitle    INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID    INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE ThisTitle.title_id=titles.title_ID  FOR XML PATH(''), TYPE).value('.', 'varchar(max)')  ,1,1,'')    FROM titles  ORDER BY title_ID …which would be turned into an UPDATE … FROM script. UPDATE titles SET  typelist= ThisTaglistFROM     (SELECT title_ID, title, STUFF(    (SELECT ','+tagname.tag FROM titles thisTitle      INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID      INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID    WHERE ThisTitle.title_id=titles.title_ID    ORDER BY CASE WHEN tagname.tag=titles.[type] THEN 1 ELSE 0  END DESC    FOR XML PATH(''), TYPE).value('.', 'varchar(max)')    ,1,1,'')  AS ThisTagList  FROM titles)fINNER JOIN Titles ON f.title_ID=Titles.title_ID You’ll notice that it isn’t quite a round trip because the tags are in a different order, though we’ve managed to make sure that the primary tag is the first one as originally. So, we’ve improved the database for the poor book distributors using PUBS. It is not a major deal but you’ve got to be prepared to provide a migration script that will go both forwards and backwards. Ideally, database refactoring scripts should be able to go from any version to any other. Schema synchronization scripts can do this pretty easily, but no data synchronisation scripts can deal with serious refactoring jobs without the developers being able to specify how to deal with cases like this.

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• Data base structure of a subscriber list

  - by foodil

  I am building a application that allow different user to store the subscriber information To store the subscriber information , the user first create a list For each list, there is a ListID. Subscriber may have different attribute : email phone fax .... For each list, their setting is different , so a require_attribute table is introduced. It is a bridge between subscriber and List That store Listid ,subid , attribute, datatype That means the system have a lot of list, each user have their own list, and the list have different attribute, some list have email , phone , some may have phone, address, name mail.. And the datatype is different, some may use 'name' as integer , some may use 'name' as varchar attribute means email phone, it is to define for which list have which subscriber attribute datatype means for each attribute, what is its datatype Table :subscriber : Field :subid , name,email Table :Require Attribute: Field : Listid ,subid , attribute, datatype The attribute here is {name, email} So a simple data is Subscriber: 1 , MYname, Myemail Require Attribute : Listid , 1 , 'email', 'intger' Listid , 1 , 'name', 'varchar' I found that this kind of storage is too complex too handle with, Since the subscriber is share to every body, so if a person want to change the datatype of name, it will also affect the data of the other user. Simple error situation: Subscriber: list1, Subscriber 1 , name1, email1 list2, Subscriber 2 , name2 , email2 Require Attribute : List1 , Subscriber 1 , 'email', 'varchar', List1 , Subscriber 1 , 'name', 'varchar', Listid , Subscriber 2 , 'email', 'varchar', Listid , Subscriber 2, 'name', 'integer', if user B change the data type of name in require attribute from varchar to integer, it cause a problem. becasue list 1 is own by user A , he want the datatype is varchar, but list 2 is won by user B , he want the datatype to be integer So how can i redesign the structure?

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• How to properly backup mediawiki database (mysql) without messing up the data?

  - by Toto

  I want to backup a mediawiki database stored in a MySQL server 5.1.36 using mysqldump. Most of the wiki articles are written in spanish and a don't want to mess up with it by creating the dump with the wrong character set. mysql> status -------------- ... Current database: wikidb Current user: root@localhost ... Server version: 5.1.36-community-log MySQL Community Server (GPL) .... Server characterset: latin1 Db characterset: utf8 Client characterset: latin1 Conn. characterset: latin1 ... Using the following command: mysql> show create table text; I see that the table create statement set the charset to binary: CREATE TABLE `text` ( `old_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `old_text` mediumblob NOT NULL, `old_flags` tinyblob NOT NULL, PRIMARY KEY (`old_id`) ) ENGINE=InnoDB AUTO_INCREMENT=317 DEFAULT CHARSET=binary MAX_ROWS=10000000 AVG_ROW_LENGTH=10240 How should I use mysqldump to properly generate a backup for that database?

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• MySQL Locking Up

  - by Ian

  I've got a innodb table that gets a lot of reads and almost no writes (like, 1 write for every 400,000 reads approx). I'm running into a pretty big problem though when I do INSERT into the table. MySQL completely locks up. It uses 100% cpu, and every single other table (in other databases even) have their statuses set to "Locked" until the INSERT is done. This is a big problem because MySQL stays locked up for up to 4 minutes. I'm using version 5.1.47 (rpm from mysql.com). Any ideas?

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• How to ignore an error in Powershell and let it continue?

  - by Jake

  I am trying to see if a process is running on multiple servers and then format it into a table. get-process -ComputerName server1,server2,server3 -name explorer | Select-Object processname,machinename Thats the easy part - When the process does not exist or if the server is unavailable, powershell outputs a big ugly error, messes up the the table and doesn't continue. Example Get-Process : Couldn't connect to remote machine.At line:1 char:12 + get-process <<<< -ComputerName server1,server2,server3 -name explorer | format-table processname,machinename + CategoryInfo : NotSpecified: (:) [Get-Process], InvalidOperatio nException + FullyQualifiedErrorId : System.InvalidOperationException,Microsoft.Power Shell.Commands.GetProcessCommand How do I get around this? If the I would still like to get notified if the process isn't available or Running.

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• One codebase - lots of hosted services (similar to a basecamp style service) - planning structure

  - by RickM

  We have built a service (PHP Based) for a client, and are now looking to offer it to other clients as a hosted service. For this example, think of it like a hosted forum service, where a client signs up on our site, and is given a subdomain or can use their own domain, and the code picks up the domain, checks it against a 'master' users table, and then loads the content as needed. I'm trying to work out the best way of handling multiple clients. At the moment I can only think of two options that would work: Option 1 - Have 1 set of database tables, but on each table have a column called 'siteid' - this would mean every query has to check the siteid. This would effectively work with just 1 codebase, and 1 database. Option 2 - Have 1 'master' database with all the core stuff such as the client details and their domain. Then when the systen checks the domain, it pulls the clients database details (username/password/dbname) from a table, and loads a second database. The issue here is security of the mysql server details, however it does have the benefit that they are running their own database instead of sharing one. Which option would I be better taking here, and why? Ideally I want it to be fairly easy to convert the 'standalone' script to the 'multi-domain' script as we're on a tight deadline.

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• Static DataTable or DataSet in a class - bad idea?

  - by Superbest

  I have several instances of a class. Each instance stores data in a common database. So, I thought "I'll make the DataTable table field static, that way every instance can just add/modify rows to its own table field, but all the data will actually be in one place!" However, apparently it's a bad idea to do use static fields, especially if it's databases: Don't Use "Static" in C#? Is this a bad idea? Will I run into problems later on if I use it? This is a small project so I can accept no testing as a compromise if that is the only drawback. The benefit of using a static database is that there can be many objects of type MyClass, but only one table they all talk to, so a static field seems to be an implementation of exactly this, while keeping syntax concise. I don't see why I shouldn't use a static field (although I wouldn't really know) but if I had to, the best alternative I can think of is creating one DataTable, and passing a reference to it when creating each instance of MyClass, perhaps as a constructor parameter. But is this really an improvement? It seems less intuitive than a static field.

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• Missing menu items for Azure SQL tables within SQL Server Management Studio?

  - by Sid

  I have a table (say Table1) that is replicated via SQL Data Sync Agent across a local SQL Server 2012 as well as an Azure SQL Server (part of Microsoft Azure). Everything about Table1 (schema, table values etc ) is identical to the best of my understanding. However, when I list and right click Table1 from Microsoft SQL Server Management Studio 2012 (SSMS), I get some very different menu options, even for seemingly basic stuff. Lets focus only on the 'Design' menu item: It is visible for Table1 on the local SQL server in SSMS It is missing for Table1 on Azure SQL via SSMS It is visible for Table1 (as Open Table Definition) on Azure SQL when reaching it via Visual Studio 2012 (Server Explorer - Data connections) This is seen in the screenshots below: Now I use scripts from some real stuff (esp when I need to check in the SQL scripts etc) but this difference concerns me to some extent. Am I witnessing just a tools artifact in SQL Server Management Studio when connecting to Azure SQL? or is it something more serious about limitations of Azure SQL itself (although, just seeing the Design surface is so basic!)?

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• SASL (Postfix) authentication with MySQL and SHA1 pre-encrypted passwords

  - by webo

  I have a Rails app with the Devise authentication gem running user registration and login. I want to use the db table that Devise populates when a user registers as the table that Postfix uses to authenticate users. The table has all the fields that Postfix may want for SASL authentication except that Devise encrypts the password using SHA1 before placing it in the database. How could I go about getting Postfix/SASL to decrypt those passwords so that the user can be authenticated properly? Devise salts the password so I'm not sure if that helps. Any suggestions? I'd likely want to do something similar with Dovecot or Courier, I'm not attached to one quite yet.

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• What relational database system should I learn? [closed]

  - by acidzombie24

  At the moment i know sqlite (my favorite), mysql (its ok, i get annoyed) and i do not want to learn ms/t sql (it only allows one nullable row if the column is unique). I am thinking about learning a new database system. My requirements for it is Must allow multiple connections at once (read and write) All or data i choose must be ACID compliant Performance should be good. I have a 17gb table in one project. It should perform well on read and transactional writes. With mysql it took hours to restore it and there were no foreign keys on that specific table. It only finished in a workday because i found a suggestion to adjust a setting which i think was key-buffer. And it still took hours Unique columns that allow more then one row to be null. I shouldn't have to say it but dammit MS. Allows one to make ongoing backups. Something like 'binary logs'. Some relatively small amounts of data i can grab and apply it to my local db to have it in sync with the one on the server. Table joins. I rather not write a bunch of queries to simulate a join What I would like but is not required Foreign keys. This may be a requirement later Open sourced Fair tool support. So i can measure queries, easily backup/restore, etc .NET and C (or C++) interface. (I seen one that uses raw tcp with JSON which was okish) Good subquery support. Once i was working with an older version of mysql (i believe <5.1 but it could have been 5.1) and i had to write many queries to do one query because it couldn't do subqueries. Or maybe it couldnt do it efficiently and died bc of memory limitations with a huge dataset. What db system should i learn?

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• Slow Inserts SQL Server 2005

  - by Achilles

  I'm researching an issue with the following information: We had a logging table with about 90k records in it that had inserts taking several seconds(approximately 10 to 20s) in extreme cases. One of the columns of the table stores XML as the XML datatype. The XML isn't being parsed during the insert, just stored. We tried truncating the table assuming that the issue was related the number of records(althought 90k seemed "normal") and the inserts still are performing poorly. While I know there are other issues that can cloud the issue, what would be some "check this first" ideas that could help me debug this issue? Thanks for any suggestions and help in advance.

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