大约有 47,000 项符合查询结果（耗时：0.0393秒） [XML]
Concatenate multiple result rows of one column into one, group by another column [duplicate]
...Simpler with the aggregate function string_agg() (Postgres 9.0 or later):
SELECT movie, string_agg(actor, ', ') AS actor_list
FROM tbl
GROUP BY 1;
The 1 in GROUP BY 1 is a positional reference and a shortcut for GROUP BY movie in this case.
string_agg() expects data type text as input. Other ...
Compare dates in MySQL
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You can try below query,
select * from players
where
us_reg_date between '2000-07-05'
and
DATE_ADD('2011-11-10',INTERVAL 1 DAY)
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SQL query to group by day
...dateadd(DAY,0, datediff(day,0, created)) return '2009-11-02 00:00:00.000'
select sum(amount) as total, dateadd(DAY,0, datediff(day,0, created)) as created
from sales
group by dateadd(DAY,0, datediff(day,0, created))
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Postgres NOT in array
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SELECT COUNT(*) FROM "messages" WHERE NOT (3 = ANY (recipient_ids))
You can always negate WHERE (condition) with WHERE NOT (condition)
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Error during installing HAXM, VT-X not working
...this, restart the computer, when the computer started then press Esc, then select the F2 if the manufacturer is dell.
Even if you have enabled the Virtualization (VT) in BIOS settings, some antivirus options prevent HAXM installation.
For example: In Avast antivirus under Settings (parameters) tab ...
How can I check if a View exists in a Database?
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FOR SQL SERVER
IF EXISTS(select * FROM sys.views where name = '')
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Map and Reduce in .NET
...ons. C# 3.5 and Linq already has it albeit under different names.
Map is Select:
Enumerable.Range(1, 10).Select(x => x + 2);
Reduce is Aggregate:
Enumerable.Range(1, 10).Aggregate(0, (acc, x) => acc + x);
Filter is Where:
Enumerable.Range(1, 10).Where(x => x % 2 == 0);
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Entity framework linq query Include() multiple children entities
...ch allows the required depth of eager loading to be specified by providing Select expressions to the appropriate depth:
using System.Data.Entity; // NB!
var company = context.Companies
.Include(co => co.Employees.Select(emp => emp.Employee_Car))
.Inc...
How to hide one item in an Android Spinner
...d spinner widget. This would allow you to simulate a spinner with no items selected, and ensures that the onItemSelected() callback is always called for every item selected (if the hidden item is the "current" one). Normally there is always one item in the spinner that doesn't generate a callback, n...
“A project with an Output type of Class Library cannot be started directly”
...oject in Solution Explorer -> Properties.
In opened tab with properties select Application and there will be ComboBox marked with Output Type label.
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