大约有 47,000 项符合查询结果（耗时：0.0389秒） [XML]
Extracting specific columns in numpy array
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I assume you wanted columns 1 and 9?
To select multiple columns at once, use
X = data[:, [1, 9]]
To select one at a time, use
x, y = data[:, 1], data[:, 9]
With names:
data[:, ['Column Name1','Column Name2']]
You can get the names from data.dtype.names…
...
Build unsigned APK file with Android Studio
...nu in the toolbar at the top (Open 'Edit Run/Debug configurations' dialog)
Select "Edit Configurations"
Click the "+"
Select "Gradle"
Choose your module as a Gradle project
In Tasks: enter assemble
Press Run
Your unsigned APK is now located in
ProjectName\app\build\outputs\apk
For detailed inf...
Random record in ActiveRecord
...he first, all after are still sorted by id). If you need multiple randomly selected records you must use this approach multiple times or use the random order method provided by your database, i.e. Thing.order("RANDOM()").limit(100) for 100 randomly selected entries. (Be aware that it's RANDOM() in P...
What is the string concatenation operator in Oracle?
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It is ||, for example:
select 'Mr ' || ename from emp;
The only "interesting" feature I can think of is that 'x' || null returns 'x', not null as you might perhaps expect.
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How can I do an UPDATE statement with JOIN in SQL Server?
...oesn't support MERGE):
ANSI/ISO:
update ud
set assid = (
select sale.assid
from sale
where sale.udid = ud.id
)
where exists (
select *
from sale
where sale.udid = ud.id
);
MySQL:
update ud u
inner join sale s on
u.id = s.udid
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Vim: How to change the highlight color for search hits and quickfix selection
... background for highlighting search hits. The same pattern is used for the selected entry in the quickfix window.
3 Answers...
Extracting hours from a DateTime (SQL Server 2005)
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SELECT DATEPART(HOUR, GETDATE());
DATEPART documentation
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SQL left join vs multiple tables on FROM line?
...nts that have employees, but always list all companies.
So you do this:
SELECT * -- for simplicity
FROM Company, Department, Employee
WHERE Company.ID *= Department.CompanyID
AND Department.ID = Employee.DepartmentID
Note that the last one there is an inner join, in order to fulfill the crite...
LEFT OUTER joins in Rails 3
...OUTER JOIN users ON users.id = posts.user_id").
joins(:blog).select
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Export query result to .csv file in SQL Server 2008
...opy the query.
In Object Explorer right-click on the database in question.
Select "Tasks" >> "Export Data..."
Configure your datasource, and click "Next".
Choose "Flat File" or "Microsoft Excel" as destination.
Specify a file path.
If working with a flat file, configure as desired. If working ...