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How do I get SUM function in MySQL to return '0' if no values are found?
...
Use COALESCE to avoid that outcome.
SELECT COALESCE(SUM(column),0)
FROM table
WHERE ...
To see it in action, please see this sql fiddle: http://www.sqlfiddle.com/#!2/d1542/3/0
More Information:
Given three tables (one with all numbers, one with all nul...
C++ 读写xml方法整理（持续更新） - C/C++ - 清泛网 - 专注C/C++及内核技术
... VARIANT_TRUE; // validates during parsing
pDoc->setProperty(_bstr_t("SelectionNamespaces"), _variant_t(g_select_namespaces)); // set select namespaces
// associate xml and schema
pDoc->schemas = pSchema.GetInterfacePtr();
// load xml file
VARIANT_BOOL vbRet = pDoc->load...
Why does Java's hashCode() in String use 31 as a multiplier?
... for 31 since 33 is not a prime:
Of the remaining
four, I'd probably select P(31), as it's the cheapest to calculate on a RISC
machine (because 31 is the difference of two powers of two). P(33) is
similarly cheap to calculate, but it's performance is marginally worse, and
33 is composit...
Array.push() if does not exist?
...
Use a js library like underscore.js for these reasons exactly. Use: union: Computes the union of the passed-in arrays: the list of unique items, in order, that are present in one or more of the arrays.
_.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
=> [1, 2, 3, 101, 10]
...
How to merge two arrays in JavaScript and de-duplicate items
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With Underscore.js or Lo-Dash you can do:
console.log(_.union([1, 2, 3], [101, 2, 1, 10], [2, 1]));
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>
http://underscorejs.org/#union
http://lodash.com/docs#union
...
How can I reliably get an object's address when operator& is overloaded?
...on operator that the type comes with.
Thus the f(T&,long) overload is selected (and the Integral Promotion performed).
What happens for any other type ?
Thus the f(T&,long) overload is selected, because there the type does not match the T* parameter.
Note: from the remarks in the fil...
Can I specify a custom location to “search for views” in ASP.NET MVC?
...t viewLocations (.Union(viewLocations)) or just change them (viewLocations.Select(path => "/AnotherPath" + path)).
To register your custom view location expander in MVC, add next lines to ConfigureServices method in Startup.cs file:
public void ConfigureServices(IServiceCollection services)
{
...
How to merge 2 List and removing duplicate values from it in C#
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Have you had a look at Enumerable.Union
This method excludes duplicates from the return set. This is different
behavior to the Concat
method, which returns all the elements
in the input sequences including
duplicates.
List<int> list1 = new List<int...
Difference between natural join and inner join
...+----------+
The INNER JOIN of TableA and TableB on Column1 will return
SELECT * FROM TableA AS a INNER JOIN TableB AS b USING (Column1);
SELECT * FROM TableA AS a INNER JOIN TableB AS b ON a.Column1 = b.Column1;
+------------+-----------+---------------------+
| a.Column1 | a.Column2 | ...
Generating random strings with T-SQL
...st varchar(8000)
declare @step bigint = rand(@seed) * 2147483647;
select @alpha = 'qwertyuiopasdfghjklzxcvbnm'
, @digit = '1234567890'
, @specials = '_@# '
select @first = @alpha + '_@';
set @seed = (rand((@seed+@step)%2147483647)*2147483647);
select @length =...