大约有 47,000 项符合查询结果（耗时：0.0393秒） [XML]
Dynamically select data frame columns using $ and a character value
...and some variable names stored in a character vector cols . When I try to select a variable from mtcars using a dynamic subset of cols , nether of these work
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Correct use of Multimapping in Dapper
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I just ran a test that works fine:
var sql = "select cast(1 as decimal) ProductId, 'a' ProductName, 'x' AccountOpened, cast(1 as decimal) CustomerId, 'name' CustomerName";
var item = connection.Query<ProductItem, Customer, ProductItem>(sql,
(p, c) => { p.Cu...
Stash only one file out of multiple files that have changed with Git?
...
You can also use git stash save -p "my commit message". This way you can select which hunks should be added to stash, whole files can be selected as well.
You'll be prompted with a few actions for each hunk:
y - stash this hunk
n - do not stash this hunk
q - quit; do not stash this hun...
Find index of last occurrence of a sub-string using T-SQL
...X, followed again by REVERSE to restore the original order. For instance:
SELECT
mf.name
,mf.physical_name
,reverse(left(reverse(physical_name), charindex('\', reverse(physical_name)) -1))
from sys.master_files mf
shows how to extract the actual database file names from from their "physic...
How to force LINQ Sum() to return 0 while source collection is empty
...word
&& l.Property.PropertyId == PropertyId)
.Select(l => l.Amount)
.DefaultIfEmpty(0)
.Sum();
This way, your query will only select the Amount field. If the collection is empty, it will return one element with the value of 0 and then the sum will ...
How do I find out my MySQL URL, host, port and username?
...If you're already logged into the command line client try this:
mysql> select user();
It will output something similar to this:
+----------------+
| user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.41 sec)
In my example above, I was logged in as root...
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 ...
Python loop counter in a for loop [duplicate]
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Use enumerate() like so:
def draw_menu(options, selected_index):
for counter, option in enumerate(options):
if counter == selected_index:
print " [*] %s" % option
else:
print " [ ] %s" % option
options = ['Option 0', 'Option...
How to allow only one radio button to be checked?
... set "groups" of radio buttons, only one radio button in each group can be selected at one time and selecting other will clear the previous selection. :)
– Shadow Wizard is Ear For You
Mar 24 '11 at 13:02
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SQLite UPSERT / UPDATE OR INSERT
... at this code:
INSERT INTO players (id, name, age)
VALUES (
coalesce((select id from players where user_name='steven'),
(select max(id) from drawings) + 1),
32)
The trick is in coalesce. It returns the id of the user 'steven' if any, and otherwise, it returns a new fresh id.
...