大约有 43,000 项符合查询结果（耗时：0.0299秒） [XML]
What's faster, SELECT DISTINCT or GROUP BY in MySQL?
...'t, then use DISTINCT.
GROUP BY in MySQL sorts results. You can even do:
SELECT u.profession FROM users u GROUP BY u.profession DESC
and get your professions sorted in DESC order.
DISTINCT creates a temporary table and uses it for storing duplicates. GROUP BY does the same, but sortes the disti...
How can I disable the UITableView selection?
When you tap a row in a UITableView , the row is highlighted and selected. Is it possible to disable this so tapping a row does nothing?
...
Should arrays be used in C++?
...only an issue for static
data, where something like:
struct Data { int i; char const* s; };
Data const ourData[] =
{
{ 1, "one" },
{ 2, "two" },
// ...
};
This is often preferable to using a vector (and std::string), since it
avoids all order of initialization issues; the data is pre...
Reference alias (calculated in SELECT) in WHERE clause
The calculated value BalanceDue that is set as a variable in the list of selected columns cannot be used in the WHERE clause.
...
Is it possible to center text in select box?
...you could style the dropdown:
https://www.filamentgroup.com/lab/jquery-ui-selectmenu-an-aria-accessible-plugin-for-styling-a-html-select.html
This plugin hides the select element, and creates span elements etc on the fly to display a custom drop down list style. I'm quite confident you'd be able t...
Retrieving the last record in each group - MySQL
...x, we can write greatest-n-per-group queries:
WITH ranked_messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTITION BY name ORDER BY id DESC) AS rn
FROM messages AS m
)
SELECT * FROM ranked_messages WHERE rn = 1;
Below is the original answer I wrote for this question in 2009:
I write the solu...
How to select the last record of a table in SQL?
This is a sample code to select all records from a table. Can someone show me how to select the last record of that table?
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How can I select rows with most recent timestamp for each key value?
...r data. Each row has a sensor id, a timestamp, and other fields. I want to select a single row with latest timestamp for each sensor, including some of the other fields.
...
Implications of foldr vs. foldl (or foldl')
...lue". I.e. remove the word "on". (Stackoverflow wouldn't let me submit a 2 char change!).
– Lqueryvg
Nov 26 '14 at 22:34
...
how to listen to N channels? (dynamic select statement)
...
You can do this using the Select function from the reflect package:
func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool)
Select executes a select operation described by the list of cases. Like
the Go select statement, it bl...