大约有 30,000 项符合查询结果（耗时：0.0392秒） [XML]
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...ate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
So what's the meaning of COUNT(1) here?
SELECT boss.boss_id, COUNT(1)
FROM boss
LEFT JOIN subordinate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
Is it this...?
-- counting all the subordinates only
SELECT boss.boss_id, COUN...
How to filter SQL results in a has-many-through relation
... the benchmarks). Not nitpicking, but perhaps you can try those queries (I mean all, not just mine) with a (student_id, club_id) (or the reverse) index.
– ypercubeᵀᴹ
Oct 18 '11 at 6:13
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Java “user.dir” property - what exactly does it mean?
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Is that mean that on tomcat configuration for all java versions if user.dir is pointing to /usr/share/tomcat and in config we add something like this: file:./config then it will be pointing to /usr/share/tomcat/config always?
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What does the slash mean in help() output?
What does the / mean in Python 3.4's help output for range before the closing parenthesis?
3 Answers
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How to reference a .css file on a razor view?
...t: It's useful to know that the second parameter in @RenderSection, false, means that the section is not required on a view that uses this master page, and the view engine will blissfully ignore the fact that there is no "Styles" section defined in your view. If true, the view won't render and an er...
Programmatically Hide/Show Android Soft Keyboard [duplicate]
... The Scroll View however makes the keyboard appear only on first startup, meaning that if you lock the screen then come back, then it will no longer be triggered. As such, I used the following stackoverflow.com/a/29229865/2413303 in order to programmatically call the keyboard (with delay, because o...
What does status=canceled for a resource mean in Chrome Developer Tools?
...ment being deleted. I know for a fact it isn't bullet point 3. What do you mean by "Once you touch the contents of an iframe, it can no longer load the resource into it"? Can you give an example?
– styfle
Nov 19 '12 at 18:11
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What is the difference between and ?
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<section> means that the content inside is grouped (i.e. relates to a single theme), and should appear as an entry in an outline of the page.
<div>, on the other hand, does not convey any meaning, aside from any found in its clas...
How do I find duplicates across multiple columns?
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Using count(*) over(partition by...) provides a simple and efficient means to locate unwanted repetition, whilst also list all affected rows and all wanted columns:
SELECT
t.*
FROM (
SELECT
s.*
, COUNT(*) OVER (PARTITION BY s.name, s.city) AS qty
FROM stuff s
) t
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Angular ng-repeat Error “Duplicates in a repeater are not allowed.”
...larjs/
AngularJS does not allow duplicates in a ng-repeat directive. This means if you are trying to do the following, you will get an error.
// This code throws the error "Duplicates in a repeater are not allowed.
// Repeater: row in [1,1,1] key: number:1"
<div ng-repeat="row in [1,1,1]">
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