大约有 40,000 项符合查询结果（耗时：0.0802秒） [XML]
postgresql COUNT(DISTINCT …) very slow
...
You can use this:
SELECT COUNT(*) FROM (SELECT DISTINCT column_name FROM table_name) AS temp;
This is much faster than:
COUNT(DISTINCT column_name)
share
|
improve this answer
...
How to show “Done” button on iPhone number pad
...onder];
numberTextField.text = @"";
}
-(void)doneWithNumberPad{
NSString *numberFromTheKeyboard = numberTextField.text;
[numberTextField resignFirstResponder];
}
share
|
improve this a...
How to check if a model has a certain column/attribute?
... a class
Use Class.column_names.include? attr_name where attr_name is the string name of your attribute.
In this case: Number.column_names.include? 'one'
For an instance
Use record.has_attribute?(:attr_name) or record.has_attribute?('attr_name') (Rails 3.2+) or record.attributes.has_key? attr_na...
What is routes.IgnoreRoute(“{resource}.axd/{*pathInfo}”)
...lers.AssemblyResourceLoader" validate="True" />
<add verb="*" path="*_AppService.axd"
Ok, so what does that handler do?
The AssemblyResourceLoader knows how to look for embedded files within an assembly so it can serve it (send it to the client i.e. a browser). For example, in asp.net web ...
How to print formatted BigDecimal values?
...
public static String currencyFormat(BigDecimal n) {
return NumberFormat.getCurrencyInstance().format(n);
}
It will use your JVM’s current default Locale to choose your currency symbol. Or you can specify a Locale.
NumberFormat.get...
How do I create a SHA1 hash in ruby?
...hat's this 'serialize' function? that's not a part of ruby. Worse yet, the string being passed to hexdigest isn't dynamic at all! This method would return the same hash regardless what data you give it!
– Blixxy
Jul 7 '12 at 10:10
...
Storing JSON in database vs. having a new column for each key
... perform a text-search on it.
value per column instead matches the whole string.
Your approach (JSON based data) is fine for data you don't need to search by, and just need to display along with your normal data.
Edit: Just to clarify, the above goes for classic relational databases. NoSQL use J...
invalid command code ., despite escaping periods, using sed
...
i used an empty string '' as the parameter for -i and that worked, like sed -i '' 's/blah/xx/g'
– Pierre Houston
Aug 29 '14 at 8:59
...
Twitter Bootstrap: Text in navbar
...ording to the twitter bootstrap documentation , I should be able to "Wrap strings of text in a <p> tag for proper leading and color." When I do this, at any level under navbar it simply doesn't inherit any of the navbar classes. Wrapping the string in <a> tags renders it but it ...
Can anyone explain IEnumerable and IEnumerator to me? [closed]
...:
// This seems reasonable ...
public class Program
{
static void Main(string[] args)
{
Console.WriteLine("***** Fun with IEnumerable / IEnumerator *****\n");
Garage carLot = new Garage();
// Hand over each car in the collection?
foreach (Car c in carLot)
{
...