大约有 43,000 项符合查询结果（耗时：0.0406秒） [XML]
Select Pandas rows based on list index
...
For large datasets, it is memory efficient to read only selected rows via the skiprows parameter.
Example
pred = lambda x: x not in [1, 3]
pd.read_csv("data.csv", skiprows=pred, index_col=0, names=...)
This will now return a DataFrame from a file that skips all rows except 1 and ...
Kill a postgresql session/connection
...user to use this function. This works on all operating systems the same.
SELECT
pg_terminate_backend(pid)
FROM
pg_stat_activity
WHERE
-- don't kill my own connection!
pid <> pg_backend_pid()
-- don't kill the connections to other databases
AND datname = 'database...
What is the difference between a stored procedure and a view?
...iece of SQL, I would define a view like:
CREATE VIEW vw_user_profile
AS
SELECT A.user_id, B.profile_description
FROM tbl_user A LEFT JOIN tbl_profile B ON A.user_id = b.user_id
GO
Thus, if I want to query profile_description by user_id in the future, all I have to do is:
SELECT profile_descr...
Vim: Creating parent directories on save
...feedback. I don't want to solve problems I don't have. I never use special chars (i.e. spaces) on my folders, so %:p:h does just fine for me. I never source vimrc (I kill and reopen vim instead) and I don't even know what pseudofiles are. redraw! doesn't seem to do anything at all to me. But I like ...
Is there a better Windows Console Window? [closed]
... the system, or copied to a folder of the program (ttf, otf, fon, bdf)
Run selected tabs as Administrator (Vista+) or as selected user
Windows 7 Jump lists and Progress on taskbar
Integration with DosBox (useful in 64bit systems to run DOS applications)
Smooth resize, maximized and fullscreen window...
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
...
How to 'insert if not exists' in MySQL?
...
Solution:
INSERT INTO `table` (`value1`, `value2`)
SELECT 'stuff for value1', 'stuff for value2' FROM DUAL
WHERE NOT EXISTS (SELECT * FROM `table`
WHERE `value1`='stuff for value1' AND `value2`='stuff for value2' LIMIT 1)
Explanation:
The innermost query
SELECT *...
Is there any way to create a blank solution (.sln) file first and then add projects?
...
Creating Solutions To create a new
solution
On the File menu, select New and then click Project.
In the Project types pane, select Other Project Types and
then select Visual Studio
Solutions.
In the Templates pane, select Blank Solution.
Enter a name for the project.
To chan...
Is it possible to select the last n items with nth-child?
Using a standard list, I'm trying to select the last 2 list items. I've various permutations of An+B but nothing seems to select the last 2:
...
Can PHP PDO Statements accept the table or column name as parameter?
... case 1:
$tbl = 'users';
break;
}
$sql = "SELECT * FROM $tbl";
}
By leaving no default case or using a default case that returns an error message you ensure that only values that you want used get used.
...