大约有 48,000 项符合查询结果（耗时：0.0170秒） [XML]
selecting unique values from a column
...you also want to output products details per date as JSON.
SELECT `date`,
CONCAT('{',GROUP_CONCAT('{\"id\": \"',`product_id`,'\",\"name\": \"',`product_name`,'\"}'),'}') as `productsJSON`
FROM `buy` group by `date`
order by `date` DESC
product_id product_name date
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Array_merge versus + [duplicate]
... instead using two new functions we wrote. "array_merge_by_key" and "array_concat" instead of a single function with a heuristic that tries to guess at what you want
– Yuliy
Jul 28 '14 at 0:38
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How to use a servlet filter in Java to change an incoming servlet request url?
...h.
Use straightforward java.lang.String methods like substring(), split(), concat() and so on to extract the part of interest and compose the new path.
Use either ServletRequest#getRequestDispatcher() and then RequestDispatcher#forward() to forward the request/response to the new URL (server-side re...
JavaScript: How to join / combine two arrays to concatenate into one array? [duplicate]
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var a = ['a','b','c'];
var b = ['d','e','f'];
var c = a.concat(b); //c is now an an array with: ['a','b','c','d','e','f']
console.log( c[3] ); //c[3] will be 'd'
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Prepend text to beginning of string
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Since we want to test prepend, and not just concatenate, I've updated the tests: jsperf.com/prepend-text-to-string/5
– metalim
Apr 22 '19 at 11:32
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const char* concatenation
I need to concatenate two const chars like these:
12 Answers
12
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What does a space mean in a CSS selector? i.e. What is the difference between .classA.classB and .cl
... Showing the failed case is helpful.
– Hal50000
Oct 23 '16 at 15:44
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Why .NET String is immutable? [duplicate]
... before StringBuilder becomes more efficient than the equivalent series of concatenations, with their inherent construction).
It would be a disadvantage if mutability was part of the purpose of an object (who'd want to be modeled by an Employee object whose salary could never ever change) though so...
Convert int to string?
... containing your integer; and then create a 3rd string that contains the 2 concated. string.Format("xyz{0}", i); on the other hand, is able to produce just 2 strings - as it's concatting them inline. This performance becomes more noticeable as the strings get longer.
– UKMonk...
SQL order string as number
... leading zeros to make all integer strings having equal length.
ORDER BY CONCAT( REPEAT( "0", 18 - LENGTH( stringfield ) ) , stringfield )
or order by part of a field something like 'tensymbols13', 'tensymbols1222' etc.
ORDER BY CONCAT( REPEAT( "0", 18 - LENGTH( LEFT( stringfield , 10 ) ) ) ...