大约有 48,000 项符合查询结果（耗时：0.0249秒） [XML]
How do you grep a file and get the next 5 lines
...ching lines.
Places a line containing a gup separator (described under --group-separator)
between contiguous groups of matches. With the -o or --only-matching
option, this has no effect and a warning is given.
-B NUM, --before-context=NUM
Print NUM lines of leading context before matching line...
Select distinct using linq [duplicate]
...
myList.GroupBy(test => test.id)
.Select(grp => grp.First());
Edit: as getting this IEnumerable<> into a List<> seems to be a mystery to many people, you can simply write:
var result = myList.GroupBy(test =...
How to store values from foreach loop into an array?
...p and use $items[] to add items to the array:
$items = array();
foreach($group_membership as $username) {
$items[] = $username;
}
print_r($items);
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Escape double quotes in parameter
...explain.
Here's a set of basic rules:
When not wrapped in double-quoted groups, spaces separate parameters:program param1 param2 param 3 will pass four parameters to program.exe: param1, param2, param, and 3.
A double-quoted group ignores spaces as value separators when passing paramete...
Laravel Eloquent groupBy() AND also return count of each group
...->select('browser', DB::raw('count(*) as total'))
->groupBy('browser')
->get();
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Grouped LIMIT in PostgreSQL: show the first N rows for each group?
I need to take the first N rows for each group, ordered by custom column.
5 Answers
5
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Real world use cases of bitwise operators [closed]
... It had pages which could be accessed by users if they were in appropriate groups. A user could be in multiple groups, so we needed to check if there was an intersection between the users groups and the pages groups. So we assigned each group a unique power-of-2 identifier, e.g.:
Group A = 1 -->...
PHP + MySQL transactions examples
...and have transactions done automatically: you still have to specific which group of queries must be executed in a transaction.
For example, quite often you'll have a couple of queries before the transaction (before the begin) and another couple of queries after the transaction (after either commit o...
How do you access the matched groups in a JavaScript regular expression?
...
You can access capturing groups like this:
var myString = "something format_abc";
var myRegexp = /(?:^|\s)format_(.*?)(?:\s|$)/g;
var match = myRegexp.exec(myString);
console.log(match[1]); // abc
And if there are multiple matches you ...
Find rows with multiple duplicate fields with Active Record, Rails & Postgres
...
Tested & Working Version
User.select(:first,:email).group(:first,:email).having("count(*) > 1")
Also, this is a little unrelated but handy. If you want to see how times each combination was found, put .size at the end:
User.select(:first,:email).group(:first,:email).havi...