大约有 48,000 项符合查询结果（耗时：0.0420秒） [XML]
COUNT DISTINCT with CONDITIONS
...
You can try this:
select
count(distinct tag) as tag_count,
count(distinct (case when entryId > 0 then tag end)) as positive_tag_count
from
your_table_name;
The first count(distinct...) is easy.
The second one, looks somewhat complex...
Why can't I reference System.ComponentModel.DataAnnotations?
...odel.DataAnnotations assembly (Solution explorer -> Add reference -> Select .Net tab -> select System.ComponentModel.DataAnnotations from the list)
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Correct use of Multimapping in Dapper
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I just ran a test that works fine:
var sql = "select cast(1 as decimal) ProductId, 'a' ProductName, 'x' AccountOpened, cast(1 as decimal) CustomerId, 'name' CustomerName";
var item = connection.Query<ProductItem, Customer, ProductItem>(sql,
(p, c) => { p.Cu...
Most efficient T-SQL way to pad a varchar on the left to a certain length?
...cely. It will also perform the conversion for you:
declare @n as int = 2
select FORMAT(@n, 'd10') as padWithZeros
Update:
I wanted to test the actual efficiency of the FORMAT function myself. I was quite surprised to find the efficiency was not very good compared to the original answer from Al...
Adding a library/JAR to an Eclipse Android project
...w application project.
When you are creating the library project, you can select any application name, package, and set other fields as needed, as shown in figure 1.
Next, set the project's properties to indicate that it is a library project:
In the Package Explorer, right-click the library proje...
How can I remove the gloss on a select element in Safari on Mac?
On Macs and iOS devices, in Safari, a <select> element with a background color generates a gloss over itself. This does not seem to happen in other operating systems.
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How to stop a program running under Eclipse?
...r. For this you can open up the devices window (in the debug perspective), select the process and then press the stop button on the same window.
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How to automatically install Emacs packages by specifying a list of package names?
...nsure keyword to install packages automatically. This also sets up package-selected-packages if you need to access the package list through customize or programatically.
– Nick McCurdy
Apr 21 '17 at 22:16
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How to force LINQ Sum() to return 0 while source collection is empty
...word
&& l.Property.PropertyId == PropertyId)
.Select(l => l.Amount)
.DefaultIfEmpty(0)
.Sum();
This way, your query will only select the Amount field. If the collection is empty, it will return one element with the value of 0 and then the sum will ...
How to do SELECT COUNT(*) GROUP BY and ORDER BY in Django?
...lvaro has answered the Django's direct equivalent for GROUP BY statement:
SELECT actor, COUNT(*) AS total
FROM Transaction
GROUP BY actor
is through the use of values() and annotate() methods as follows:
Transaction.objects.values('actor').annotate(total=Count('actor')).order_by()
However ...