大约有 47,000 项符合查询结果（耗时：0.0482秒） [XML]
Group by month and year in MySQL
...
I prefer
SELECT
MONTHNAME(t.summaryDateTime) as month, YEAR(t.summaryDateTime) as year
FROM
trading_summary t
GROUP BY EXTRACT(YEAR_MONTH FROM t.summaryDateTime) DESC";
...
Force Intellij IDEA to reread all maven dependencies
...le project and I do this. Does this command apply to all modules, just the selected one, or the first one in the project when it runs?
– slartibartfast
Sep 25 '15 at 22:06
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When to use single quotes, double quotes, and backticks in MySQL
...ng query will produce different results (or errors) depending on SQL mode:
SELECT "column" FROM table WHERE foo = "bar"
ANSI_QUOTES disabled
The query will select the string literal "column" where column foo is equal to string "bar"
ANSI_QUOTES enabled
The query will select the column column where ...
How to find a table having a specific column in postgresql
...
you can query system catalogs:
select c.relname
from pg_class as c
inner join pg_attribute as a on a.attrelid = c.oid
where a.attname = <column name> and c.relkind = 'r'
sql fiddle demo
...
How to remove a key from Hash and get the remaining hash in Ruby/Rails?
...m a hash and get the remaining hash in Ruby.
.slice => It will return selected keys and not delete them from the original hash. Use slice! if you want to remove the keys permanently else use simple slice.
2.2.2 :074 > hash = {"one"=>1, "two"=>2, "three"=>3}
=> {"one"=>1, "tw...
How many database indexes is too many?
...
It depends on the operations that occur on the table.
If there's lots of SELECTs and very few changes, index all you like.... these will (potentially) speed the SELECT statements up.
If the table is heavily hit by UPDATEs, INSERTs + DELETEs ... these will be very slow with lots of indexes since t...
Is there a difference between copy initialization and direct initialization?
...ain function :
int main()
{
A a1 = 1; // OK: copy-initialization selects A::A(int)
A a2(2); // OK: direct-initialization selects A::A(int)
A a3 {4, 5}; // OK: direct-list-initialization selects A::A(int, int)
A a4 = {4, 5}; // OK: copy-list-initialization selects A::A(i...
How do I convert an enum to a list in C#? [duplicate]
...er way:
Enum.GetValues(typeof(SomeEnum))
.Cast<SomeEnum>()
.Select(v => v.ToString())
.ToList();
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What's the Point of Multiple Redis Databases?
...e instances lets you take advantage of multiple cores. If you use database selection you will have to refactor when upgrading. Monitoring and managing multiple instances is not difficult nor painful.
Indeed, you would get far better metrics on each db by segregation based on instance. Each instanc...
What is a method group in C#?
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Also, if you are using LINQ, you can apparently do something like myList.Select(methodGroup).
So, for example, I have:
private string DoSomethingToMyString(string input)
{
// blah
}
Instead of explicitly stating the variable to be used like this:
public List<string> GetStringStuff()...