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scanning

Scanning is the default search option for small tables.

Enter text here to perform a scan over supported column types.

Text columns with limited length use a substring search If the entered text is a number, integer columns will be scanned for an exact match of the value.

The scanning search option is disabled for large tables.

seeking

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.

In the single-column case, the database will seek to the position the entered search term would be at and return all rows greater or equal to that value.

In the multiple-column case, the above still applies to the column you supplied non-empty search text for. All previous columns, however, will be using an equality match.

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Note that there are some explanatory texts on larger screens.

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  1. POConvert Decimal to Double?
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    1. USEggs McLaren
  2. POPercentage width child element in absolutely positioned parent on Internet Explorer 7
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    1. USKevin Dente
  3. POHow do I calculate someone's age in C#?
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  4. POCalculate relative time in C#
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  5. PODetermine a User's Timezone
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    1. USKevin Dente
  6. PODifference between Math.Floor() and Math.Truncate()
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    1. USAnonymous User
  7. POFilling a DataSet or DataTable from a LINQ query result set
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    <p>How do you expose a LINQ query as an ASMX web service? Usually, from the business tier, I can return a typed <code>DataSet</code> or <code>DataTable</code> which can be serialized for transport over ASMX.</p> <p>How can I do the same for a LINQ query? Is there a way to populate a typed <code>DataSet</code> or <code>DataTable</code> via a LINQ query?</p> <pre><code>public static MyDataTable CallMySproc() { string conn = "..."; MyDatabaseDataContext db = new MyDatabaseDataContext(conn); MyDataTable dt = new MyDataTable(); // execute a sproc via LINQ var query = from dr in db.MySproc().AsEnumerable select dr; // copy LINQ query resultset into a DataTable -this does not work ! dt = query.CopyToDataTable(); return dt; } </code></pre> <p>How can I get the result set of a LINQ query into a <code>DataSet</code> or <code>DataTable</code>? Alternatively, is the LINQ query serializeable so that I can expose it as an ASMX web service?</p>
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    1. USNhan
    1. USGeoff Dalgas
  8. POBinary Data in MySQL
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  9. POWhat is the fastest way to get the value of π?
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    <p>I'm looking for the fastest way to obtain the value of π, as a personal challenge. More specifically, I'm using ways that don't involve using <code>#define</code> constants like <code>M_PI</code>, or hard-coding the number in.</p> <p>The program below tests the various ways I know of. The inline assembly version is, in theory, the fastest option, though clearly not portable. I've included it as a baseline to compare against the other versions. In my tests, with built-ins, the <code>4 * atan(1)</code> version is fastest on GCC 4.2, because it auto-folds the <code>atan(1)</code> into a constant. With <code>-fno-builtin</code> specified, the <code>atan2(0, -1)</code> version is fastest.</p> <p>Here's the main testing program (<code>pitimes.c</code>):</p> <pre class="lang-c prettyprint-override"><code>#include &lt;math.h&gt; #include &lt;stdio.h&gt; #include &lt;time.h&gt; #define ITERS 10000000 #define TESTWITH(x) { \ diff = 0.0; \ time1 = clock(); \ for (i = 0; i &lt; ITERS; ++i) \ diff += (x) - M_PI; \ time2 = clock(); \ printf("%s\t=&gt; %e, time =&gt; %f\n", #x, diff, diffclock(time2, time1)); \ } static inline double diffclock(clock_t time1, clock_t time0) { return (double) (time1 - time0) / CLOCKS_PER_SEC; } int main() { int i; clock_t time1, time2; double diff; /* Warmup. The atan2 case catches GCC's atan folding (which would * optimise the ``4 * atan(1) - M_PI'' to a no-op), if -fno-builtin * is not used. */ TESTWITH(4 * atan(1)) TESTWITH(4 * atan2(1, 1)) #if defined(__GNUC__) &amp;&amp; (defined(__i386__) || defined(__amd64__)) extern double fldpi(); TESTWITH(fldpi()) #endif /* Actual tests start here. */ TESTWITH(atan2(0, -1)) TESTWITH(acos(-1)) TESTWITH(2 * asin(1)) TESTWITH(4 * atan2(1, 1)) TESTWITH(4 * atan(1)) return 0; } </code></pre> <p>And the inline assembly stuff (<code>fldpi.c</code>) that will only work for x86 and x64 systems:</p> <pre class="lang-c prettyprint-override"><code>double fldpi() { double pi; asm("fldpi" : "=t" (pi)); return pi; } </code></pre> <p>And a build script that builds all the configurations I'm testing (<code>build.sh</code>):</p> <pre><code>#!/bin/sh gcc -O3 -Wall -c -m32 -o fldpi-32.o fldpi.c gcc -O3 -Wall -c -m64 -o fldpi-64.o fldpi.c gcc -O3 -Wall -ffast-math -m32 -o pitimes1-32 pitimes.c fldpi-32.o gcc -O3 -Wall -m32 -o pitimes2-32 pitimes.c fldpi-32.o -lm gcc -O3 -Wall -fno-builtin -m32 -o pitimes3-32 pitimes.c fldpi-32.o -lm gcc -O3 -Wall -ffast-math -m64 -o pitimes1-64 pitimes.c fldpi-64.o -lm gcc -O3 -Wall -m64 -o pitimes2-64 pitimes.c fldpi-64.o -lm gcc -O3 -Wall -fno-builtin -m64 -o pitimes3-64 pitimes.c fldpi-64.o -lm </code></pre> <p>Apart from testing between various compiler flags (I've compared 32-bit against 64-bit too, because the optimisations are different), I've also tried switching the order of the tests around. But still, the <code>atan2(0, -1)</code> version still comes out on top every time.</p>
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    1. USChris Jester-Young
    1. USChris Jester-Young
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Querying!

 
Guidance
A table list

Lists show table rows with slightly less information than detail views, therefore not requiring section labels.

This list shows the beginning of an entire table.

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.

Loading more

Loading more rows than the initial 10 results is also currently restricted to a single reloading of 100 entries.

A future version will keep auto-loading on scroll for tables that have suitable indexes.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

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