大约有 47,000 项符合查询结果（耗时：0.0387秒） [XML]
MySQL query to get column names?
... DESCRIBE cannot be used with WHERE. For example : SHOW COLUMNS FROM acct__order WHERE ``Key`` = 'PRI'; to get the Primary key of a table is not working with DESCRIBE.
– Meloman
Sep 2 at 11:45
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How do you reverse a string in place in C or C++?
... XOR swapping is slower than swapping via register on modern out-of-order processors.
– Patrick Schlüter
Aug 15 '11 at 17:42
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Exact time measurement for performance testing [duplicate]
...= Environment.TickCount; was used as input to the algorithm under test, in order to make it non-deterministic and prevent it from being evaluated at compile-time. That seed is not being used here.
– piedar
Nov 7 '19 at 16:55
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How to make ng-repeat filter out duplicate results
...nd use it directly in the ng-options (or ng-repeat).
<select ng-model="orderProp" ng-options="place.category for place in places | unique:'category'">
<option value="0">Default</option>
// unique options from the categories
</select>
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Return 0 if field is null in MySQL
... Would that be IFNULL((SELECT SUM(uop.price * uop.qty) FROM uc_order_products uop WHERE uo.order_id = uop.order_id) AS products_subtotal, 0)?
– Kevin
Oct 22 '10 at 13:46
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Why does i = i + i give me 0?
...rator -.
If an integer addition overflows, then the result is the low-order
bits of the mathematical sum as represented in some sufficiently large
two's-complement format. If overflow occurs, then the sign of the
result is not the same as the sign of the mathematical sum of the two
oper...
PHP exec() vs system() vs passthru()
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Remove elements from collection while iterating
...ection, which would imply a second iteration work to look for this item in order to remove it.
I think it is worth mentioning that the remove method of the Iterator interface is marked as "optional" in Javadocs, which means that there could be Iterator implementations that throw UnsupportedOperatio...
Retrieving the last record in each group - MySQL
...TH 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 solution this way:
SELECT m1.*
FROM messages m1 LEFT...
How to get the top 10 values in postgresql?
...
For this you can use limit
select *
from scores
order by score desc
limit 10
If performance is important (when is it not ;-) look for an index on score.
Starting with version 8.4, you can also use the standard (SQL:2008) fetch first
select *
from scores
order by scor...