大约有 5,880 项符合查询结果（耗时：0.0376秒） [XML]
Why should C++ programmers minimize use of 'new'?
...omposes. It scales.
If you use the Line class as a building block:
class Table
{
Line borders[4];
};
Then
int main ()
{
Table table;
}
allocates four std::string instances, four Line instances, one Table instance and all the string's contents and everything is freed automagically...
NSLog the method name with Objective-C in iPhone
...t because the Objective-C runtime is dynamic, it's actually using a lookup table to figure out which method on which class to call so a char* is convenient since methods are represented as strings in the lookup table.
– Jack Lawrence
Nov 7 '12 at 16:42
...
How to read data when some numbers contain commas as thousand separator?
...
You can have read.table or read.csv do this conversion for you semi-automatically. First create a new class definition, then create a conversion function and set it as an "as" method using the setAs function like so:
setClass("num.with.commas...
MYSQL OR vs IN performance
...s the same.
$t = microtime(true);
for($i=0; $i<10000; $i++):
$q = DB::table('users')->where('id',1)
->orWhere('id',2)
->orWhere('id',3)
->orWhere('id',4)
->orWhere('id',5)
->orWhere('id',6)
->orWhere('id',7)
->orWhere('id',8)
->orWhere(...
How to find the statistical mode?
... hope it's helpful. It is also what I was thinking anyways. You'll want to table() the data, sort and then pick the first name. It's hackish but should work.
names(sort(-table(x)))[1]
share
|
impr...
Why should I capitalize my SQL keywords? [duplicate]
...nk the latter is more readable. You can easily separate the keywords from table and column names, etc.
share
|
improve this answer
|
follow
|
...
How can I get a list of all functions stored in the database of a particular schema in PostgreSQL?
...
After some searching, I was able to find the information_schema.routines table and the information_schema.parameters tables. Using those, one can construct a query for this purpose. LEFT JOIN, instead of JOIN, is necessary to retrieve functions without parameters.
SELECT routines.routine_name, pa...
How to implement a unique index on two columns in rails
I have a table and I'm trying to add a unique index on two columns. Those columns are also indexed. So my question is if I just can remove the indexes who were just for one column or if I have to use all three indexes:
...
Why is the Fibonacci series used in agile planning poker? [closed]
...nd verbal description in the software domain is closer to the one shown in Table 3 than to Saaty’s." And in this table we see that something is called "slightly bigger" if it is 125% of the base size and it is called "bigger", if it is 175% of the base size.
– asmaier
...
What is the difference between a database and a data warehouse?
... as Data Warehousing. This records the data from the user for history.
The tables and joins are complex since they are normalized (for RDMS). This is done to reduce redundant data and to save storage space.
Entity – Relational modeling techniques are used for RDMS database design.
Optimized for wr...