大约有 43,000 项符合查询结果（耗时：0.0452秒） [XML]
LINQ's Distinct() on a particular property
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(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
HashSet<TKey> seenKeys = new HashSet<TKey>();
foreach (TSource element in source)
{
if (seenKeys.Add(keySelector(element)))
{
yield return element;
}
...
How to reset sequence in postgres and fill id column with new data?
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SELECT setval('seq', 1, FALSE) should do the same (here, the third argument, FALSE, does the magic, as it shows that nextval must be 1 instead of 2)
– Vasilen Donchev
Sep 22 '15 at 14:43...
How do you kill all current connections to a SQL Server 2005 database?
...problems ALTER DATABASE aspnetdb SET SINGLE_USER WITH ROLLBACK IMMEDIATE select GETDATE() ALTER DATABASE aspnetdb SET MULTI_USER what do you have instead of the commented out code?
– SQLMenace
Aug 17 '10 at 18:33
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how to check the dtype of a column in python pandas
...know this is a bit of an old thread but with pandas 19.02, you can do:
df.select_dtypes(include=['float64']).apply(your_function)
df.select_dtypes(exclude=['string','object']).apply(your_other_function)
http://pandas.pydata.org/pandas-docs/version/0.19.2/generated/pandas.DataFrame.select_dtypes.h...
String.equals versus == [duplicate]
...ject, but it would be equally valid to replace "Hello" with new String(new char[] {'H', 'e', ...})
– parasietje
Sep 19 '13 at 9:46
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SQL Server Linked Server Example Query
...a Linked Server in SSMS Object Explorer, right-click, and Script Table as, SELECT To, and New Query Editor Window. The resulting SELECT statement will include the correct, fully-qualified path to the table. I had a mystery database qualifier in working with Sybase and this gave me the correct name.
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Core dumped, but core file is not in the current directory?
...ore_pattern is used to specify a core dumpfile pattern name.
If the first character of the pattern is a '|', the kernel will treat
the rest of the pattern as a command to run. The core dump will be
written to the standard input of that program instead of to a file.
Instead of writing the core du...
List of tables, db schema, dump etc using the Python sqlite3 API
....tab
job snmptarget t1 t2 t3
sqlite> select name from sqlite_master where type = 'table';
job
t1
t2
snmptarget
t3
sqlite> .schema job
CREATE TABLE job (
id INTEGER PRIMARY KEY,
data VARCHAR
);
sqlite> select sql from sqlite_master where type = 'ta...
Mac SQLite editor [closed]
... info.plist and setting it to YES
Running the app on a device
Open iTunes
Select the device
Select the "Apps" tab
Scroll down to the "File Sharing" section and select the app
The .sqlite file should appear in the right hand pane - select it and "Save to..."
Once it's saved open it up in your favour...
Replacement for “rename” in dplyr
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The next version of dplyr will support an improved version of select that also incorporates renaming:
> mtcars2 <- select( mtcars, disp2 = disp )
> head( mtcars2 )
disp2
Mazda RX4 160
Mazda RX4 Wag 160
Datsun 710 108
Hornet 4 Drive 258
H...