大约有 41,000 项符合查询结果（耗时：0.0460秒） [XML]
How do I use ROW_NUMBER()?
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For the first question, why not just use?
SELECT COUNT(*) FROM myTable
to get the count.
And for the second question, the primary key of the row is what should be used to identify a particular row. Don't try and use the row number for that.
If you returned Ro...
Android Spinner: Get the selected item change event
How can you set the event listener for a Spinner when the selected item changes?
16 Answers
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Simple way to calculate median with MySQL
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In MariaDB / MySQL:
SELECT AVG(dd.val) as median_val
FROM (
SELECT d.val, @rownum:=@rownum+1 as `row_number`, @total_rows:=@rownum
FROM data d, (SELECT @rownum:=0) r
WHERE d.val is NOT NULL
-- put some where clause here
ORDER BY d.val
) ...
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...for all your queries that need to count everything, even for joins, use *
SELECT boss.boss_id, COUNT(subordinate.*)
FROM boss
LEFT JOIN subordinate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
But don't use COUNT(*) for LEFT joins, as that will return 1 even if the subordinate table doe...
Swift - Split string over multiple lines
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This still works, but you need to manually add the \n character. For example, in the REPL: println("foo\n" + "bar") prints foo and bar on separate lines.
– Brian Gerstle
Jul 8 '15 at 17:41
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Remove outline from select box in FF
Is it possible to remove the dotted line surrounding a selected item in a select element?
12 Answers
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How to use clock() in C++
...0;
int min = 0;
int hr = 0;
//cout << "Press any key to start:";
//char start = _gtech();
for (;;)
{
newline();
if(msec == 1000)
{
++sec;
msec = 0;
}
if(sec == 60)
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Why do I get “unresolved external symbol” errors when using templates? [duplicate]
...ings like basic_string<T> you're only ever going to be using it with char or wchar_t so if putting all the implementation in the header is a concern, instantiating it in the cpp is an option. The code is yours to command, not vice-versa.
– shoosh
Oct 31 ...
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.
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Weird Integer boxing in Java
... section 5.1.7:
If the value p being boxed is true,
false, a byte, a char in the range
\u0000 to \u007f, or an int or short
number between -128 and 127, then let
r1 and r2 be the results of any two
boxing conversions of p. It is always
the case that r1 == r2.
The discussion goes on...