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  • performance of parameterized queries for different db's

    - by tuinstoel
    A lot of people know that it is important to use parameterized queries to prevent sql injection attacks. Parameterized queries are also much faster in sqlite and oracle when doing online transaction processing because the query optimizer doesn't have to reparse every parameterized sql statement before executing. I've seen sqlite becoming 3 times faster when you use parameterized queries, oracle can become 10 times faster when you use parameterized queries in some extreme cases with a lot of concurrency. How about other db's like mysql, ms sql, db2 and postgresql? Is there an equal difference in performance between parameterized queries and literal queries?

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  • Mobile Friendly Websites with CSS Media Queries

    - by dwahlin
    In a previous post the concept of CSS media queries was introduced and I discussed the fundamentals of how they can be used to target different screen sizes. I showed how they could be used to convert a 3-column wide page into a more vertical view of data that displays better on devices such as an iPhone:     In this post I'll provide an additional look at how CSS media queries can be used to mobile-enable a sample site called "Widget Masters" without having to change any server-side code or HTML code. The site that will be discussed is shown next:     This site has some of the standard items shown in most websites today including a title area, menu bar, and sections where data is displayed. Without including CSS media queries the site is readable but has to be zoomed out to see everything on a mobile device, cuts-off some of the menu items, and requires horizontal scrolling to get to additional content. The following image shows what the site looks like on an iPhone. While the site works on mobile devices it's definitely not optimized for mobile.     Let's take a look at how CSS media queries can be used to override existing styles in the site based on different screen widths. Adding CSS Media Queries into a Site The Widget Masters Website relies on standard CSS combined with HTML5 elements to provide the layout shown earlier. For example, to layout the menu bar shown at the top of the page the nav element is used as shown next. A standard div element could certainly be used as well if desired.   <nav> <ul class="clearfix"> <li><a href="#home">Home</a></li> <li><a href="#products">Products</a></li> <li><a href="#aboutus">About Us</a></li> <li><a href="#contactus">Contact Us</a></li> <li><a href="#store">Store</a></li> </ul> </nav>   This HTML is combined with the CSS shown next to add a CSS3 gradient, handle the horizontal orientation, and add some general hover effects.   nav { width: 100%; } nav ul { border-radius: 6px; height: 40px; width: 100%; margin: 0; padding: 0; background: rgb(125,126,125); /* Old browsers */ background: -moz-linear-gradient(top, rgba(125,126,125,1) 0%, rgba(14,14,14,1) 100%); /* FF3.6+ */ background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(125,126,125,1)), color-stop(100%,rgba(14,14,14,1))); /* Chrome,Safari4+ */ background: -webkit-linear-gradient(top, rgba(125,126,125,1) 0%, rgba(14,14,14,1) 100%); /* Chrome10+,Safari5.1+ */ background: -o-linear-gradient(top, rgba(125,126,125,1) 0%, rgba(14,14,14,1) 100%); /* Opera 11.10+ */ background: -ms-linear-gradient(top, rgba(125,126,125,1) 0%, rgba(14,14,14,1) 100%); /* IE10+ */ background: linear-gradient(top, rgba(125,126,125,1) 0%, rgba(14,14,14,1) 100%); /* W3C */ filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#7d7e7d', endColorstr='#0e0e0e',GradientType=0 ); /* IE6-9 */ } nav ul > li { list-style: none; float: left; margin: 0; padding: 0; } nav ul > li:first-child { margin-left: 8px; } nav ul > li > a { color: #ccc; text-decoration: none; line-height: 2.8em; font-size: 0.95em; font-weight: bold; padding: 8px 25px 7px 25px; font-family: Arial, Helvetica, sans-serif; } nav ul > li a:hover { background-color: rgba(0, 0, 0, 0.1); color: #fff; }   When mobile devices hit the site the layout of the menu items needs to be adjusted so that they're all visible without having to swipe left or right to get to them. This type of modification can be accomplished using CSS media queries by targeting specific screen sizes. To start, a media query can be added into the site's CSS file as shown next: @media screen and (max-width:320px) { /* CSS style overrides for this screen width go here */ } This media query targets screens that have a maximum width of 320 pixels. Additional types of queries can also be added – refer to my previous post for more details as well as resources that can be used to test media queries in different devices. In that post I emphasize (and I'll emphasize again) that CSS media queries only modify the overall layout and look and feel of a site. They don't optimize the site as far as the size of the images or content sent to the device which is important to keep in mind. To make the navigation menu more accessible on devices such as an iPhone or Android the CSS shown next can be used. This code changes the height of the menu from 40 pixels to 100%, takes off the li element floats, changes the line-height, and changes the margins.   @media screen and (max-width:320px) { nav ul { height: 100%; } nav ul > li { float: none; } nav ul > li a { line-height: 1.5em; } nav ul > li:first-child { margin-left: 0px; } /* Additional CSS overrides go here */ }   The following image shows an example of what the menu look like when run on a device with a width of 320 pixels:   Mobile devices with a maximum width of 480 pixels need different CSS styles applied since they have 160 additional pixels of width. This can be done by adding a new CSS media query into the stylesheet as shown next. Looking through the CSS you'll see that only a minimal override is added to adjust the padding of anchor tags since the menu fits by default in this screen width.   @media screen and (max-width: 480px) { nav ul > li > a { padding: 8px 10px 7px 10px; } }   Running the site on a device with 480 pixels results in the menu shown next being rendered. Notice that the space between the menu items is much smaller compared to what was shown when the main site loads in a standard browser.     In addition to modifying the menu, the 3 horizontal content sections shown earlier can be changed from a horizontal layout to a vertical layout so that they look good on a variety of smaller mobile devices and are easier to navigate by end users. The HTML5 article and section elements are used as containers for the 3 sections in the site as shown next:   <article class="clearfix"> <section id="info"> <header>Why Choose Us?</header> <br /> <img id="mainImage" src="Images/ArticleImage.png" title="Article Image" /> <p> Post emensos insuperabilis expeditionis eventus languentibus partium animis, quas periculorum varietas fregerat et laborum, nondum tubarum cessante clangore vel milite locato per stationes hibernas. </p> </section> <section id="products"> <header>Products</header> <br /> <img id="gearsImage" src="Images/Gears.png" title="Article Image" /> <p> <ul> <li>Widget 1</li> <li>Widget 2</li> <li>Widget 3</li> <li>Widget 4</li> <li>Widget 5</li> </ul> </p> </section> <section id="FAQ"> <header>FAQ</header> <br /> <img id="faqImage" src="Images/faq.png" title="Article Image" /> <p> <ul> <li>FAQ 1</li> <li>FAQ 2</li> <li>FAQ 3</li> <li>FAQ 4</li> <li>FAQ 5</li> </ul> </p> </section> </article>   To force the sections into a vertical layout for smaller mobile devices the CSS styles shown next can be added into the media queries targeting 320 pixel and 480 pixel widths. Styles to target the display size of the images in each section are also included. It's important to note that the original image is still being downloaded from the server and isn't being optimized in any way for the mobile device. It's certainly possible for the CSS to include URL information for a mobile-optimized image if desired. @media screen and (max-width:320px) { section { float: none; width: 97%; margin: 0px; padding: 5px; } #wrapper { padding: 5px; width: 96%; } #mainImage, #gearsImage, #faqImage { width: 100%; height: 100px; } } @media screen and (max-width: 480px) { section { float: none; width: 98%; margin: 0px 0px 10px 0px; padding: 5px; } article > section:last-child { margin-right: 0px; float: none; } #bottomSection { width: 99%; } #wrapper { padding: 5px; width: 96%; } #mainImage, #gearsImage, #faqImage { width: 100%; height: 100px; } }   The following images show the site rendered on an iPhone with the CSS media queries in place. Each of the sections now displays vertically making it much easier for the user to access them. Images inside of each section also scale appropriately to fit properly.     CSS media queries provide a great way to override default styles in a website and target devices with different resolutions. In this post you've seen how CSS media queries can be used to convert a standard browser-based site into a site that is more accessible to mobile users. Although much more can be done to optimize sites for mobile, CSS media queries provide a nice starting point if you don't have the time or resources to create mobile-specific versions of sites.

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  • 7 Habits of Highly Effective Media Queries - by Brad Frost

    - by ihaynes
    Originally posted on: http://geekswithblogs.net/ihaynes/archive/2013/10/11/7-habits-of-highly-effective-media-queries---by-brad.aspxBrad Frost, one of the original proponents of responsive design, has written a great article on the "7 Habits of Highly Effective Media Queries".Let content determine breakpointsTreat layout as an enhancementUse major and minor breakpointsUse relative unitsGo beyond widthUse media queries for conditional loadingDon't go overboardGot you wondering? Read Brad's full article.Oh, and if you haven't read Steven Covey's original "7 Habits of Highly Effective People" book, it's a valuable read too, and might just change the way you relate to others and the world around you.

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  • Whether to use UNION or OR in SQL Server Queries

    - by Dinesh Asanka
    Recently I came across with an article on DB2 about using Union instead of OR. So I thought of carrying out a research on SQL Server on what scenarios UNION is optimal in and which scenarios OR would be best. I will analyze this with a few scenarios using samples taken  from the AdventureWorks database Sales.SalesOrderDetail table. Scenario 1: Selecting all columns So we are going to select all columns and you have a non-clustered index on the ProductID column. --Query 1 : OR SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 OR ProductID =709 OR ProductID =998 OR ProductID =875 OR ProductID =976 OR ProductID =874 --Query 2 : UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 709 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 998 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 875 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 976 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 874 So query 1 is using OR and the later is using UNION. Let us analyze the execution plans for these queries. Query 1 Query 2 As expected Query 1 will use Clustered Index Scan but Query 2, uses all sorts of things. In this case, since it is using multiple CPUs you might have CX_PACKET waits as well. Let’s look at the profiler results for these two queries: CPU Reads Duration Row Counts OR 78 1252 389 3854 UNION 250 7495 660 3854 You can see from the above table the UNION query is not performing well as the  OR query though both are retuning same no of rows (3854).These results indicate that, for the above scenario UNION should be used. Scenario 2: Non-Clustered and Clustered Index Columns only --Query 1 : OR SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 714 OR ProductID =709 OR ProductID =998 OR ProductID =875 OR ProductID =976 OR ProductID =874 GO --Query 2 : UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 714 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 709 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 998 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 875 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 976 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 874 GO So this time, we will be selecting only index columns, which means these queries will avoid a data page lookup. As in the previous case we will analyze the execution plans: Query 1 Query 2 Again, Query 2 is more complex than Query 1. Let us look at the profile analysis: CPU Reads Duration Row Counts OR 0 24 208 3854 UNION 0 38 193 3854 In this analyzis, there is only slight difference between OR and UNION. Scenario 3: Selecting all columns for different fields Up to now, we were using only one column (ProductID) in the where clause.  What if we have two columns for where clauses and let us assume both are covered by non-clustered indexes? --Query 1 : OR SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 OR CarrierTrackingNumber LIKE 'D0B8%' --Query 2 : UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 UNION SELECT * FROM Sales.SalesOrderDetail WHERE CarrierTrackingNumber  LIKE 'D0B8%' Query 1 Query 2: As we can see, the query plan for the second query has improved. Let us see the profiler results. CPU Reads Duration Row Counts OR 47 1278 443 1228 UNION 31 1334 400 1228 So in this case too, there is little difference between OR and UNION. Scenario 4: Selecting Clustered index columns for different fields Now let us go only with clustered indexes: --Query 1 : OR SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 OR CarrierTrackingNumber LIKE 'D0B8%' --Query 2 : UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 UNION SELECT * FROM Sales.SalesOrderDetail WHERE CarrierTrackingNumber  LIKE 'D0B8%' Query 1 Query 2 Now both execution plans are almost identical except is an additional Stream Aggregate is used in the first query. This means UNION has advantage over OR in this scenario. Let us see profiler results for these queries again. CPU Reads Duration Row Counts OR 0 319 366 1228 UNION 0 50 193 1228 Now see the differences, in this scenario UNION has somewhat of an advantage over OR. Conclusion Using UNION or OR depends on the scenario you are faced with. So you need to do your analyzing before selecting the appropriate method. Also, above the four scenarios are not all an exhaustive list of scenarios, I selected those for the broad description purposes only.

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  • Using CSS3 media queries in HTML 5 pages

    - by nikolaosk
    This is going to be the seventh post in a series of posts regarding HTML 5. You can find the other posts here , here , here, here , here and here. In this post I will provide a hands-on example on how to use CSS 3 Media Queries in HTML 5 pages. This is a very important feature since nowadays lots of users view websites through their mobile devices. Web designers were able to define media-specific style sheets for quite a while, but have been limited to the type of output. The output could only be Screen, Print .The way we used to do things before CSS 3 was to have separate CSS files and the browser decided which style sheet to use. Please have a look at the snippet below - HTML 4 media queries <link rel="stylesheet" type="text/css" media="screen" href="styles.css"> <link rel="stylesheet" type="text/css" media="print" href="print-styles.css"> ?he browser determines which style to use. With CSS 3 we can have all media queries in one stylesheet. Media queries can determine the resolution of the device, the orientation of the device, the width and height of the device and the width and height of the browser window.We can also include CSS 3 media queries in separate stylesheets. In order to be absolutely clear this is not (and could not be) a detailed tutorial on HTML 5. There are other great resources for that.Navigate to the excellent interactive tutorials of W3School. Another excellent resource is HTML 5 Doctor. Two very nice sites that show you what features and specifications are implemented by various browsers and their versions are http://caniuse.com/ and http://html5test.com/. At this times Chrome seems to support most of HTML 5 specifications.Another excellent way to find out if the browser supports HTML 5 and CSS 3 features is to use the Javascript lightweight library Modernizr. In this hands-on example I will be using Expression Web 4.0.This application is not a free application. You can use any HTML editor you like.You can use Visual Studio 2012 Express edition. You can download it here. Before I go on with the actual demo I will use the (http://www.caniuse.com) to see the support for CSS 3 Media Queries from the latest versions of modern browsers. Please have a look at the picture below. We see that all the latest versions of modern browsers support this feature. We can see that even IE 9 supports this feature.   Let's move on with the actual demo.  This is going to be a rather simple demo.I create a simple HTML 5 page. The markup follows and it is very easy to use and understand.This is a page with a 2 column layout. <!DOCTYPE html><html lang="en">  <head>    <title>HTML 5, CSS3 and JQuery</title>    <meta http-equiv="Content-Type" content="text/html;charset=utf-8" >    <link rel="stylesheet" type="text/css" href="style.css">       </head>  <body>    <div id="header">      <h1>Learn cutting edge technologies</h1>      <p>HTML 5, JQuery, CSS3</p>    </div>    <div id="main">      <div id="mainnews">        <div>          <h2>HTML 5</h2>        </div>        <div>          <p>            HTML5 is the latest version of HTML and XHTML. The HTML standard defines a single language that can be written in HTML and XML. It attempts to solve issues found in previous iterations of HTML and addresses the needs of Web Applications, an area previously not adequately covered by HTML.          </p>          <div class="quote">            <h4>Do More with Less</h4>            <p>             jQuery is a fast and concise JavaScript Library that simplifies HTML document traversing, event handling, animating, and Ajax interactions for rapid web development.             </p>            </div>          <p>            The HTML5 test(html5test.com) score is an indication of how well your browser supports the upcoming HTML5 standard and related specifications. Even though the specification isn't finalized yet, all major browser manufacturers are making sure their browser is ready for the future. Find out which parts of HTML5 are already supported by your browser today and compare the results with other browsers.                      The HTML5 test does not try to test all of the new features offered by HTML5, nor does it try to test the functionality of each feature it does detect. Despite these shortcomings we hope that by quantifying the level of support users and web developers will get an idea of how hard the browser manufacturers work on improving their browsers and the web as a development platform.</p>        </div>      </div>              <div id="CSS">        <div>          <h2>CSS 3 Intro</h2>        </div>        <div>          <p>          Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation semantics (the look and formatting) of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can also be applied to any kind of XML document, including plain XML, SVG and XUL.          </p>        </div>      </div>            <div id="CSSmore">        <div>          <h2>CSS 3 Purpose</h2>        </div>        <div>          <p>            CSS is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation, including elements such as the layout, colors, and fonts.[1] This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple pages to share formatting, and reduce complexity and repetition in the structural content (such as by allowing for tableless web design).          </p>        </div>      </div>                </div>    <div id="footer">        <p>Feel free to google more about the subject</p>      </div>     </body>  </html>    The CSS code (style.css) follows  body{        line-height: 30px;        width: 1024px;        background-color:#eee;      }            p{        font-size:17px;    font-family:"Comic Sans MS"      }      p,h2,h3,h4{        margin: 0 0 20px 0;      }            #main, #header, #footer{        width: 100%;        margin: 0px auto;        display:block;      }            #header{        text-align: center;         border-bottom: 1px solid #000;         margin-bottom: 30px;      }            #footer{        text-align: center;         border-top: 1px solid #000;         margin-bottom: 30px;      }            .quote{        width: 200px;       margin-left: 10px;       padding: 5px;       float: right;       border: 2px solid #000;       background-color:#F9ACAE;      }            .quote :last-child{        margin-bottom: 0;      }            #main{        column-count:2;        column-gap:20px;        column-rule: 1px solid #000;        -moz-column-count: 2;        -webkit-column-count: 2;        -moz-column-gap: 20px;        -webkit-column-gap: 20px;        -moz-column-rule: 1px solid #000;        -webkit-column-rule: 1px solid #000;      } Now I view the page in the browser.Now I am going to write a media query and add some more rules in the .css file in order to change the layout of the page when the page is viewed by mobile devices. @media only screen and (max-width: 480px) {          body{            width: 480px;          }          #main{            -moz-column-count: 1;            -webkit-column-count: 1;          }        }   I am specifying that this media query applies only to screen and a max width of 480 px. If this condition is true, then I add new rules for the body element. I change the number of columns to one. This rule will not be applied unless the maximum width is 480px or less.  As I decrease the size-width of the browser window I see no change in the column's layout. Have a look at the picture below. When I resize the window and the width of the browser so the width is less than 480px, the media query and its respective rules take effect.We can scroll vertically to view the content which is a more optimised viewing experience for mobile devices. Have a look at the picture below Hope it helps!!!!

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  • Parameterized SQL statements vs. very simple method

    - by Philipp G
    When I started to write the first SQL-Statements in my programs I felt quite comfortable with protecting myself against SQL-Injection with a very simple method that a colleague showed me. It replaced all single quotes with two single quotes. So for example there is a searchfield in which you can enter a customername to search in the customertable. If you would enter Peter's Barbershop The SELECT Statement would look like SELECT * FROM Customers WHERE Customername = 'Peter''s Barbershop' If now an attacker would insert this: ';DROP TABLE FOO; -- The statement would look like: SELECT * FROM Customers WHERE Customername = ''';DROP TABLE FOO;--' It would not drop any table, but search the customertable for the customername ';DROP TABLE FOO;-- which, I suppose, won't be found ;-) Now after a while of writing statements and protecting myself against SQL-Injection with this method, I read that many developers use parameterized statements, but I never read an article where "our" method was used. So definitely there is a good reason for it. What scenarios would parameterized statements cover but our method doesn't? What are the advantages of parameterized statements compared to our method? Thanks Philipp

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  • Responsive Design: Media Query Bookmarket - shows the applied media queries and current window size

    - by ihaynes
    Originally posted on: http://geekswithblogs.net/ihaynes/archive/2013/06/19/153181.aspxThere are any number of tools for resizing the browser window to check responsive designs. One that stands out for me is the Media Query Bookmarklet from the Sparkbox Foundry. This shows you the currently applied media queries and browser size in both pixels and ems. Once you've used this you'll wonder how you managed without it.Note: The main page says in works in Chrome and Safari. It also works in IE10.Details at http://seesparkbox.com/foundry/media_query_bookmarklet

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  • Finding the SQL output of a parameterized query

    - by Dan Monego
    I'm making a parameterized query using C# against a SQL server 2005 instance, and I'd like to take a look at the SQL that is run against the database for debugging purposes. Is there somewhere I can look to see what the output SQL of the parameterized command is, either in the database logs or in the Visual Studio debugger?

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  • Optimizing data downloaded via 'link' media queries and asynchronous loading

    - by adam-asdf
    I have a website that tries to make sensible use of media queries and avoid 'expensive' CSS for users of mobile devices. My eventual goal is to make it 'mobile-first' but for now, since it is based on Twitter Bootstrap it isn't. I included some background images (Base64 encoded) and styles that would only apply to "full-size" browsers in a separate stylesheet loaded asynchronously via modernizr.load. In Firefox (but not webkit browsers) it makes it so that if you navigate away from the homepage and then return, the content (specifically, all those extras) 'blinks' when it finishes loading...or maybe I should say reloading. If, instead of using modernizr.load, I include that stylesheet via a link... in the head with a media query attribute will it prevent the data from being downloaded by non-matching browsers (mobile, based on screensize) that it is inapplicable to?

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  • android:junit running Parameterized testcases.

    - by puneetinderkaur
    Hi, i wan to run a single testcase with different parameters. in java it possible through junit4 and code is like this package com.android.test; import static org.junit.Assert.assertEquals; import java.util.Arrays; import java.util.Collection; import org.junit.Test; import org.junit.runner.RunWith; import org.junit.runners.Parameterized; import org.junit.runners.Parameterized.Parameters; @RunWith(Parameterized.class) public class ParameterizedTestExample { private int number; private int number2; private int result; private functioncall coun; //constructor takes parameters from array public ParameterizedTestExample(int number, int number2, int result1) { this.number = number; this.number2 = number2; this.result = result1; coun = new functioncall(); } //array with parameters @Parameters public static Collection<Object[]> data() { Object[][] data = new Object[][] { { 1, 4, 5 }, { 2, 7, 9 }, { 3, 7, 10 }, { 4, 9, 13 } }; return Arrays.asList(data); } //running our test @Test public void testCounter() { assertEquals("Result add x y", result, coun.calculateSum(this.number, this.number2), 0); } } Now my question is can we Run the same with android testcases where we have deal with context. when i try to run the code using android junit. it gives me error NoClassDefinationFound.

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  • Scheduling parameterized reports in Crystal Reports Server

    - by SarekOfVulcan
    I'm trying to set up a report to run monthly in Crystal Reports Server 2008 that will give me the next month's Affordable Care Plan termination dates. However, as far as I can tell, I can only give it a particular date string, not "7 days after the report is scheduled". How do I do this? (Same question for CR2008, actually, but the server is the one I'm interested in right now.) Thanks!

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  • When optimizing database queries, what exactly is the relationship between number of queries and siz

    - by williamjones
    To optimize application speed, everyone always advises to minimize the number of queries an application makes to the database, consolidating them into fewer queries that retrieve more wherever possible. However, this also always comes with the caution that data transferred is still data transferred, and just because you are making fewer queries doesn't make the data transferred free. I'm in a situation where I can over-include on the query in order to cut down the number of queries, and simply remove the unwanted data in the application code. Is there any type of a rule of thumb on how much of a cost there is to each query, to know when to optimize number of queries versus size of queries? I've tried to Google for objective performance analysis data, but surprisingly haven't been able to find anything like that. Clearly this relationship will change for factors such as when the database grows in size, making this somewhat individualized, but surely this is not so individualized that a broad sense of the landscape can't be drawn out? I'm looking for general answers, but for what it's worth, I'm running an application on Heroku.com, which means Ruby on Rails with a Postgres database.

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  • Parameterized Queries /Without/ using queries.

    - by Aren B
    I've got a bit of a poor situation here. I'm stuck working with commerce server, which doesn't do a whole lot of sanitization/parameterization. I'm trying to build up my queries to prevent SQL Injection, however some things like the searches / where clause on the search object need to be built up, and there's no parameterized interface. Basically, I cannot parameterize, however I was hoping to be able to use the same engine to BUILD my query text if possible. Is there a way to do this, aside from writing my own parameterizing engine which will probably still not be as good as parameterized queries? Update: Example The where clause has to be built up as a sql query where clause essentially: CatalogSearch search = /// Create Search object from commerce server search.WhereClause = string.Format("[cy_list_price] > {0} AND [Hide] is not NULL AND [DateOfIntroduction] BETWEEN '{1}' AND '{2}'", 12.99m, DateTime.Now.AddDays(-2), DateTime.Now); *Above Example is how you refine the search, however we've done some testing, this string is NOT SANITIZED. This is where my problem lies, because any of those inputs in the .Format could be user input, and while i can clean up my input from text-boxes easily, I'm going to miss edge cases, it's just the nature of things. I do not have the option here to use a parameterized query because Commerce Server has some insane backwards logic in how it handles the extensible set of fields (schema) & the free-text search words are pre-compiled somewhere. This means I cannot go directly to the sql tables What i'd /love/ to see is something along the lines of: SqlCommand cmd = new SqlCommand("[cy_list_price] > @MinPrice AND [DateOfIntroduction] BETWEEN @StartDate AND @EndDate"); cmd.Parameters.AddWithValue("@MinPrice", 12.99m); cmd.Parameters.AddWithValue("@StartDate", DateTime.Now.AddDays(-2)); cmd.Parameters.AddWithValue("@EndDate", DateTime.Now); CatalogSearch search = /// constructor search.WhereClause = cmd.ToSqlString();

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  • Queries within queries: Is there a better way?

    - by mririgo
    As I build bigger, more advanced web applications, I'm finding myself writing extremely long and complex queries. I tend to write queries within queries a lot because I feel making one call to the database from PHP is better than making several and correlating the data. However, anyone who knows anything about SQL knows about JOINs. Personally, I've used a JOIN or two before, but quickly stopped when I discovered using subqueries because it felt easier and quicker for me to write and maintain. Commonly, I'll do subqueries that may contain one or more subqueries from relative tables. Consider this example: SELECT (SELECT username FROM users WHERE records.user_id = user_id) AS username, (SELECT last_name||', '||first_name FROM users WHERE records.user_id = user_id) AS name, in_timestamp, out_timestamp FROM records ORDER BY in_timestamp Rarely, I'll do subqueries after the WHERE clause. Consider this example: SELECT user_id, (SELECT name FROM organizations WHERE (SELECT organization FROM locations WHERE records.location = location_id) = organization_id) AS organization_name FROM records ORDER BY in_timestamp In these two cases, would I see any sort of improvement if I decided to rewrite the queries using a JOIN? As more of a blanket question, what are the advantages/disadvantages of using subqueries or a JOIN? Is one way more correct or accepted than the other?

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  • Ouput all the page's media queries in a list

    - by alecrust
    Using JavaScript, what would be the best way to output a list containing all media queries that are being applied to the current page. I assume this would need to filtering to find embedded media queries i.e. <link rel="stylesheet" media="only screen and (min-width: 30em)" href="/css/30em.css"> as well as media queries located in CSS files, i.e. @media only screen and (min-width: 320px) {} An example output of what I'm looking for: <p>There are 3 media queries loaded on this page</p> <ol> <li>30em</li> <li>40em</li> <li>960px</li> </ol>

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  • How can I view live MySQL queries?

    - by barfoon
    Hey all, I am just wondering if its possible to trace MySQL queries on my linux server as they happen? For example I'd love to set up some sort of listener, then request a web page and view all of the queries the engine executed, or just view all of the queries being run on a production server. Are there tools to do this? Thank you,

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  • Entity Framework Batch Update and Future Queries

    - by pwelter34
    Entity Framework Extended Library A library the extends the functionality of Entity Framework. Features Batch Update and Delete Future Queries Audit Log Project Package and Source NuGet Package PM> Install-Package EntityFramework.Extended NuGet: http://nuget.org/List/Packages/EntityFramework.Extended Source: http://github.com/loresoft/EntityFramework.Extended Batch Update and Delete A current limitations of the Entity Framework is that in order to update or delete an entity you have to first retrieve it into memory. Now in most scenarios this is just fine. There are however some senerios where performance would suffer. Also, for single deletes, the object must be retrieved before it can be deleted requiring two calls to the database. Batch update and delete eliminates the need to retrieve and load an entity before modifying it. Deleting //delete all users where FirstName matches context.Users.Delete(u => u.FirstName == "firstname"); Update //update all tasks with status of 1 to status of 2 context.Tasks.Update( t => t.StatusId == 1, t => new Task {StatusId = 2}); //example of using an IQueryable as the filter for the update var users = context.Users .Where(u => u.FirstName == "firstname"); context.Users.Update( users, u => new User {FirstName = "newfirstname"}); Future Queries Build up a list of queries for the data that you need and the first time any of the results are accessed, all the data will retrieved in one round trip to the database server. Reducing the number of trips to the database is a great. Using this feature is as simple as appending .Future() to the end of your queries. To use the Future Queries, make sure to import the EntityFramework.Extensions namespace. Future queries are created with the following extension methods... Future() FutureFirstOrDefault() FutureCount() Sample // build up queries var q1 = db.Users .Where(t => t.EmailAddress == "[email protected]") .Future(); var q2 = db.Tasks .Where(t => t.Summary == "Test") .Future(); // this triggers the loading of all the future queries var users = q1.ToList(); In the example above, there are 2 queries built up, as soon as one of the queries is enumerated, it triggers the batch load of both queries. // base query var q = db.Tasks.Where(t => t.Priority == 2); // get total count var q1 = q.FutureCount(); // get page var q2 = q.Skip(pageIndex).Take(pageSize).Future(); // triggers execute as a batch int total = q1.Value; var tasks = q2.ToList(); In this example, we have a common senerio where you want to page a list of tasks. In order for the GUI to setup the paging control, you need a total count. With Future, we can batch together the queries to get all the data in one database call. Future queries work by creating the appropriate IFutureQuery object that keeps the IQuerable. The IFutureQuery object is then stored in IFutureContext.FutureQueries list. Then, when one of the IFutureQuery objects is enumerated, it calls back to IFutureContext.ExecuteFutureQueries() via the LoadAction delegate. ExecuteFutureQueries builds a batch query from all the stored IFutureQuery objects. Finally, all the IFutureQuery objects are updated with the results from the query. Audit Log The Audit Log feature will capture the changes to entities anytime they are submitted to the database. The Audit Log captures only the entities that are changed and only the properties on those entities that were changed. The before and after values are recorded. AuditLogger.LastAudit is where this information is held and there is a ToXml() method that makes it easy to turn the AuditLog into xml for easy storage. The AuditLog can be customized via attributes on the entities or via a Fluent Configuration API. Fluent Configuration // config audit when your application is starting up... var auditConfiguration = AuditConfiguration.Default; auditConfiguration.IncludeRelationships = true; auditConfiguration.LoadRelationships = true; auditConfiguration.DefaultAuditable = true; // customize the audit for Task entity auditConfiguration.IsAuditable<Task>() .NotAudited(t => t.TaskExtended) .FormatWith(t => t.Status, v => FormatStatus(v)); // set the display member when status is a foreign key auditConfiguration.IsAuditable<Status>() .DisplayMember(t => t.Name); Create an Audit Log var db = new TrackerContext(); var audit = db.BeginAudit(); // make some updates ... db.SaveChanges(); var log = audit.LastLog;

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  • How to avoid this PDO exception: Cannot execute queries while other unbuffered queries are active

    - by Vittorio Vittori
    Hi, I'd like to print a simple table in my page with 3 columns, building name, tags and architecture style. If I try to retrieve the list of building names and arch. styles there is no problem: SELECT buildings.name, arch_styles.style_name FROM buildings INNER JOIN buildings_arch_styles ON buildings.id = buildings_arch_styles.building_id INNER JOIN arch_styles ON arch_styles.id = buildings_arch_styles.arch_style_id LIMIT 0, 10 My problem starts on retreaving the first 5 tags for every building of the query I've just wrote. SELECT DISTINCT name FROM tags INNER JOIN buildings_tags ON buildings_tags.tag_id = tags.id AND buildings_tags.building_id = 123 LIMIT 0, 5 The query itself works perfectly, but not where I thought to use it: <?php // pdo connection allready active, i'm using mysql $pdo_conn->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true); $sql = "SELECT buildings.name, buildings.id, arch_styles.style_name FROM buildings INNER JOIN buildings_arch_styles ON buildings.id = buildings_arch_styles.building_id INNER JOIN arch_styles ON arch_styles.id = buildings_arch_styles.arch_style_id LIMIT 0, 10"; $buildings_stmt = $pdo_conn->prepare ($sql); $buildings_stmt->execute (); $buildings = $buildings_stmt->fetchAll (PDO::FETCH_ASSOC); $sql = "SELECT DISTINCT name FROM tags INNER JOIN buildings_tags ON buildings_tags.tag_id = tags.id AND buildings_tags.building_id = :building_id LIMIT 0, 5"; $tags_stmt = $pdo_conn->prepare ($sql); $html = "<table>"; // i'll use it to print my table foreach ($buildings as $building) { $name = $building["name"]; $style = $building["style_name"]; $id = $building["id"]; $tags_stmt->bindParam (":building_id", $id, PDO::PARAM_INT); $tags_stmt->execute (); // the problem is HERE $tags = $tags_stmt->fetchAll (PDO::FETCH_ASSOC); $html .= "... $name ... $style"; foreach ($tags as $current_tag) { $tag = $current_tag["name"]; $html .= "... $tag ..."; // let's suppose this is an area of the table where I print the first 5 tags per building } } $html .= "...</table>"; print $html; I'm not experienced on queries, so i though something like this, but it throws the error: PHP Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute. What can I do to avoid this? Should I change all and search a different way to get this kind of queries?

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  • Handling multiple media queries in Sass with Twitter Bootstrap

    - by Keith
    I have a Sass mixin for my media queries based on Twitter Bootstrap's responsive media queries: @mixin respond-to($media) { @if $media == handhelds { /* Landscape phones and down */ @media (max-width: 480px) { @content; } } @else if $media == small { /* Landscape phone to portrait tablet */ @media (max-width: 767px) {@content; } } @else if $media == medium { /* Portrait tablet to landscape and desktop */ @media (min-width: 768px) and (max-width: 979px) { @content; } } @else if $media == large { /* Large desktop */ @media (min-width: 1200px) { @content; } } @else { @media only screen and (max-width: #{$media}px) { @content; } } } And I call them throughout my SCSS file like so: .link { color:blue; @include respond-to(medium) { color: red; } } However, sometimes I want to style multiple queries with the same styles. Right now I'm doing them like this: .link { color:blue; /* this is fine for handheld and small sizes*/ /*now I want to change the styles that are cascading to medium and large*/ @include respond-to(medium) { color: red; } @include respond-to(large) { color: red; } } but I'm repeating code so I'm wondering if there is a more concise way to write it so I can target multiple queries. Something like this so I don't need to repeat my code (I know this doesn't work): @include respond-to(medium, large) { color: red; } Any suggestions on the best way to handle this?

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  • LINQ to SQL: ExecuteQuery not working when performing a parameterized query.

    - by ajbeaven
    I have a weird problem with ExecuteQuery in that it isn't working when performing a parameterized query. The following returns 1 record: db.ExecuteQuery<Member>(@"SELECT * FROM Member INNER JOIN aspnet_Users ON Member.user_id = aspnet_Users.UserId WHERE [aspnet_Users].[UserName] = 'Marina2'"); However, the parameterized version returns no results: db.ExecuteQuery<Member>(@"SELECT * FROM Member INNER JOIN aspnet_Users ON Member.user_id = aspnet_Users.UserId WHERE [aspnet_Users].[UserName] = '{0}'", "Marina2"); What am I doing wrong?

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  • Junit Parameterized tests together with Powermock - how!?

    - by Subtwo
    Hi! I've been trying to figure out how to run parameterized tests in Junit4 together with PowerMock. The problem is that to use PowerMock you need to decorate your test class with @RunWith(PowerMock.class) and to use parameterized tests you have to decorate with @RunWith(Parameterized.class) From what I can see they seem mutually excluded!? Is this true? Is there any way around this? I've tried to create a parameterized class within a class running with PowerMock; something like this: @RunWith(PowerMock.class) class MyTestClass { @RunWith(Parameterized.class) class ParamTestClass { // Yadayada } } But unfortunately this doesn't do much good... The ParamTestClass still doesn't run with PowerMock support (not that surprisingly maybe)... And I've kind of run out of ideas so any help is greatly appreciated!

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  • do's and don'ts for writing mysql queries

    - by nik
    One thing I always wonder while writing query is that am I writing most optimized query or not? I know certain things like: 1) using SELECT field1, filed2 instead of SELECT * 2) Giving proper indexes to the tables but I am sure there are more things that should be kept in mind for writing queries, since most of the database can only grow more and optimal query will help gr8 in execution time, Can u share some tips and tricks on writing queries?

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  • I get 2014 Cannot execute queries while other unbuffered queries are active when doing exec with PDO

    - by Itay Moav
    I am doing a PDO::exec command on multiple updates: $MyPdo->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY,true); $MyPdo->exec("update t1 set f1=1;update t2 set f1=2"); I am doing it inside a transaction, and I keep getting: SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute. those are the only query/ies

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  • Best way to optimize queries like this in Django

    - by chris
    I am trying to lower the amount of queries that my django app is using, but I am a little confused on how to do it. I would like to get a query set with one hit to the database and then filter items from that set. I have tried a couple of things, but I always get queries for each set. let's say I want to get all names from my DB, but also separate out the people just named Ted. Both the names and the ted set will be used in the template. This will give me two sets, one with all names and one with Ted.. but also hits the database twice: namelist = People.objects.all() tedList = namelist.filter(name='ted') Is there a way to filter the first set without hitting the data base again?

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