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Seeking is the default search option for large tables.

Seeking requires indexes and can only be done using the column (or columns) the index is defined on.

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plurals
  1. PO
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    1. POConvert Decimal to Double?
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    1. USKevin Dente
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    <p>Here's how I do it</p> <pre class="lang-csharp prettyprint-override"><code>var ts = new TimeSpan(DateTime.UtcNow.Ticks - dt.Ticks); double delta = Math.Abs(ts.TotalSeconds); if (delta &lt; 60) { return ts.Seconds == 1 ? "one second ago" : ts.Seconds + " seconds ago"; } if (delta &lt; 120) { return "a minute ago"; } if (delta &lt; 2700) // 45 * 60 { return ts.Minutes + " minutes ago"; } if (delta &lt; 5400) // 90 * 60 { return "an hour ago"; } if (delta &lt; 86400) // 24 * 60 * 60 { return ts.Hours + " hours ago"; } if (delta &lt; 172800) // 48 * 60 * 60 { return "yesterday"; } if (delta &lt; 2592000) // 30 * 24 * 60 * 60 { return ts.Days + " days ago"; } if (delta &lt; 31104000) // 12 * 30 * 24 * 60 * 60 { int months = Convert.ToInt32(Math.Floor((double)ts.Days / 30)); return months &lt;= 1 ? "one month ago" : months + " months ago"; } int years = Convert.ToInt32(Math.Floor((double)ts.Days / 365)); return years &lt;= 1 ? "one year ago" : years + " years ago"; </code></pre> <p>Suggestions? Comments? Ways to improve this algorithm?</p>
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    1. POCalculate relative time in C#
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    1. USKnickerless-Noggins
    1. USJeff Atwood
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    <p>For a table like this:</p> <pre><code>CREATE TABLE binary_data ( id INT(4) NOT NULL AUTO_INCREMENT PRIMARY KEY, description CHAR(50), bin_data LONGBLOB, filename CHAR(50), filesize CHAR(50), filetype CHAR(50) ); </code></pre> <p>Here is a PHP example:</p> <pre><code>&lt;?php // store.php3 - by Florian Dittmer &lt;dittmer@gmx.net&gt; // Example php script to demonstrate the storing of binary files into // an sql database. More information can be found at http://www.phpbuilder.com/ ?&gt; &lt;html&gt; &lt;head&gt;&lt;title&gt;Store binary data into SQL Database&lt;/title&gt;&lt;/head&gt; &lt;body&gt; &lt;?php // Code that will be executed if the form has been submitted: if ($submit) { // Connect to the database (you may have to adjust // the hostname, username or password). mysql_connect("localhost", "root", "password"); mysql_select_db("binary_data"); $data = mysql_real_escape_string(fread(fopen($form_data, "r"), filesize($form_data))); $result = mysql_query("INSERT INTO binary_data (description, bin_data, filename, filesize, filetype) ". "VALUES ('$form_description', '$data', '$form_data_name', '$form_data_size', '$form_data_type')"); $id= mysql_insert_id(); print "&lt;p&gt;This file has the following Database ID: &lt;b&gt;$id&lt;/b&gt;"; mysql_close(); } else { // else show the form to submit new data: ?&gt; &lt;form method="post" action="&lt;?php echo $PHP_SELF; ?&gt;" enctype="multipart/form-data"&gt; File Description:&lt;br&gt; &lt;input type="text" name="form_description" size="40"&gt; &lt;input type="hidden" name="MAX_FILE_SIZE" value="1000000"&gt; &lt;br&gt;File to upload/store in database:&lt;br&gt; &lt;input type="file" name="form_data" size="40"&gt; &lt;p&gt;&lt;input type="submit" name="submit" value="submit"&gt; &lt;/form&gt; &lt;?php } ?&gt; &lt;/body&gt; &lt;/html&gt; </code></pre>
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    1. POBinary Data in MySQL
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    1. USmauris
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    <p>Many years ago, to provide an <a href="http://cloud9.hedgee.com/age" rel="noreferrer">age calculator gimmick</a> on my website, I wrote a function to calculate age to a fraction. This is a quick port of that function to C# (from <a href="http://hedgee.svn.sourceforge.net/viewvc/hedgee/trunk/chris/ckwww/ckage.php3" rel="noreferrer">the PHP version</a>). I'm afraid I haven't been able to test the C# version, but hope you enjoy all the same!</p> <p>(Admittedly this is a bit gimmicky for the purposes of showing user profiles on Stack Overflow, but maybe readers will find some use for it. :-))</p> <pre><code>double AgeDiff(DateTime date1, DateTime date2) { double years = date2.Year - date1.Year; /* * If date2 and date1 + round(date2 - date1) are on different sides * of 29 February, then our partial year is considered to have 366 * days total, otherwise it's 365. Note that 59 is the day number * of 29 Feb. */ double fraction = 365 + (DateTime.IsLeapYear(date2.Year) &amp;&amp; date2.DayOfYear &gt;= 59 &amp;&amp; (date1.DayOfYear &lt; 59 || date1.DayOfYear &gt; date2.DayOfYear) ? 1 : 0); /* * The only really nontrivial case is if date1 is in a leap year, * and date2 is not. So let's handle the others first. */ if (DateTime.IsLeapYear(date2.Year) == DateTime.IsLeapYear(date1.Year)) return years + (date2.DayOfYear - date1.DayOfYear) / fraction; /* * If date2 is in a leap year, but date1 is not and is March or * beyond, shift up by a day. */ if (DateTime.IsLeapYear(date2.Year)) { return years + (date2.DayOfYear - date1.DayOfYear - (date1.DayOfYear &gt;= 59 ? 1 : 0)) / fraction; } /* * If date1 is not on 29 February, shift down date1 by a day if * March or later. Proceed normally. */ if (date1.DayOfYear != 59) { return years + (date2.DayOfYear - date1.DayOfYear + (date1.DayOfYear &gt; 59 ? 1 : 0)) / fraction; } /* * Okay, here date1 is on 29 February, and date2 is not on a leap * year. What to do now? On 28 Feb in date2's year, the ``age'' * should be just shy of a whole number, and on 1 Mar should be * just over. Perhaps the easiest way is to a point halfway * between those two: 58.5. */ return years + (date2.DayOfYear - 58.5) / fraction; } </code></pre>
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    1. POHow do I calculate someone's age in C#?
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    1. USChris Jester-Young
    1. USChris Jester-Young
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    1. POHow do I calculate someone's age in C#?
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    1. USNick Berardi
    1. USNick Berardi
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    1. POBinary Data in MySQL
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    1. USMat
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    <p>@jeff</p> <p>IMHO yours seems a little long. However it does seem a little more robust with support for "yesterday" and "years". But in my experience when this is used the person is most likely to view the content in the first 30 days. It is only the really hardcore people that come after that. So that is why I usually elect to keep this short and simple.</p> <p>This is the method I am currently using on one of my websites. This only returns a relative day, hour, time. And then the user has to slap on "ago" in the output.</p> <pre><code>public static string ToLongString(this TimeSpan time) { string output = String.Empty; if (time.Days &gt; 0) output += time.Days + " days "; if ((time.Days == 0 || time.Days == 1) &amp;&amp; time.Hours &gt; 0) output += time.Hours + " hr "; if (time.Days == 0 &amp;&amp; time.Minutes &gt; 0) output += time.Minutes + " min "; if (output.Length == 0) output += time.Seconds + " sec"; return output.Trim(); } </code></pre>
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    1. USNick Berardi
    1. USNick Berardi
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    1. PODetermine a User's Timezone
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    1. USMads Kristiansen
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    1. POHow to use the C socket API in C++ on z/OS
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    1. USChris Jester-Young
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Search

Searching on lists works via indexes when the table is large. On the left you see input fields generated from viable indexes and an expandable report for all indexes that are unavailable for searching with the respective reasons.

Searching along indexes is called seeking and this is one of the main values that databases offer. The trivial alternative is scanning, which is potentially inefficient as it works by walking the entirety of the candidate rows to find the matches.

The offer to scan is given for small tables. Currently, this only works on text and integer columns and they are searched all at once.

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