大约有 40,000 项符合查询结果（耗时：0.0359秒） [XML]
Postgresql GROUP_CONCAT equivalent?
...
Note that the syntax also allows you to specify the order of values in the string (or array, using array_agg) e.g. string_agg(some_column, ',' ORDER BY some_column) or even string_agg(surname || ', ' || forename, '; ' ORDER BY surname, forename)
– IMSoP
...
How to find gaps in sequential numbering in mysql?
... Note: This query doesn't work on temporary tables. My problem was the order number I was searching for gaps in is not distinct (the table stores order lines, so the order number they belong to repeats for each line). 1st query: 2812 rows in set (1 min 31.09 sec). Made another table by selecting...
DDD - the rule that Entities can't access Repositories directly
...e complicated validation rules. Let's say you're Amazon.com. Have you ever ordered something with an expired credit card? I have, where I haven't updated the card and bought something. It accepts the order and the UI informs me that everything is peachy. About 15 minutes later, I'll get an e-mail sa...
Disable all table constraints in Oracle
...NABLED'
AND NOT (t.iot_type IS NOT NULL AND c.constraint_type = 'P')
ORDER BY c.constraint_type DESC)
LOOP
dbms_utility.exec_ddl_statement('alter table "' || c.owner || '"."' || c.table_name || '" disable constraint ' || c.constraint_name);
END LOOP;
END;
/
Enabling the constraints a...
Thread-safe List property
...
ConcurrentBag is unordered collection, so unlike List<T> it does not guarantee ordering. Also you cannot access items by index.
– Radek Stromský
Mar 7 '13 at 13:56
...
Shuffle two list at once with same order
...nts and documents2 I have the same documents and I need shuffle them in order to keep same order in both lists. I cannot shuffle them separately because each time I shuffle the list, I get other results. That is why I need to shuffle the at once with same order because I need compare them in the ...
What is the difference between HashSet and List?
...SymmetricExceptWith(hashSet2);//hashSet1 -> 4, 5, 6
By the way, the order is not preserved in HashSets. In the example, we added element "2" last but it is in the second order:
HashSet<string> hashSet1 = new HashSet<string>() { "3", "4", "8" };
hashSet1.Add("1"); // 3, 4, 8, 1...
Panel.Dock Fill ignoring other Panel.Dock setting
...l, it may fill the entire form, ignoring the first panel. Changing the tab order does nothing.
10 Answers
...
Factors in R: more than an annoyance?
...y they are useful because model fitting packages like lme4 use factors and ordered factors to differentially fit models and determine the type of contrasts to use. And graphing packages also use them to group by. ggplot and most model fitting functions coerce character vectors to factors, so the res...
Accessing a Dictionary.Keys Key through a numeric index
...t = mydict.Keys.ElementAt(mydict.Count -1);
You should not depend on the order of keys in a Dictionary. If you need ordering, you should use an OrderedDictionary, as suggested in this answer. The other answers on this page are interesting as well.
...