大约有 40,000 项符合查询结果（耗时：0.0740秒） [XML]
ActiveRecord: size vs count
...l valid.
You'll adapt the function you use depending on your needs.
Basically:
if you already load all entries, say User.all, then you should use length to avoid another db query
if you haven't anything loaded, use count to make a count query on your db
if you don't want to bother with these con...
How does a public key verify a signature?
... add a digital signature to a document using his/her private key to essentially obtain a hash of the document, but what I do not understand is how the public key can be used to verify that signature.
...
Find element's index in pandas Series
... The trouble here is it assumes the element being searched for is actually in the list. It's a bummer pandas doesn't seem to have a built in find operation.
– jxramos
Aug 23 '17 at 17:16
...
Difference between TCP and UDP?
...TCP is a connection oriented stream over an IP network. It guarantees that all sent packets will reach the destination in the correct order. This imply the use of acknowledgement packets sent back to the sender, and automatic retransmission, causing additional delays and a general less efficient tra...
Count characters in textarea
... relevance of IDs of textarea and second span : id="post" <-> id="rem_post" and the title of the span that holds the desired characters amount of each particular textarea
<textarea class="countit" name="post" id="post"></textarea>
<p>
<span>characters remaining: <...
Using GCC to produce readable assembly?
...is nice:
-r shows symbol names on relocations (so you'd see puts in the call instruction below)
-R shows dynamic-linking relocations / symbol names (useful on shared libraries)
-C demangles C++ symbol names
-w is "wide" mode: it doesn't line-wrap the machine-code bytes
-Mintel: use GAS/binutils MA...
How to find index of list item in Swift?
...B = arr.indexOf("b") // 1
let indexOfD = arr.indexOf("d") // nil
Additionally, finding the first element in an array fulfilling a predicate is supported by another extension of CollectionType:
let arr2 = [1,2,3,4,5,6,7,8,9,10]
let indexOfFirstGreaterThanFive = arr2.indexOf({$0 > 5}) // 5
let i...
Including all the jars in a directory within the Java classpath
Is there a way to include all the jar files within a directory in the classpath?
25 Answers
...
Real life example, when to use OUTER / CROSS APPLY in SQL
... ORDER BY pr.name) pa
ORDER BY pr.name,
pa.name
2) Calling a Table Valued Function for each row in the outer query
SELECT *
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle)
3) Reusing a column alias
SELECT number,
doubled_number...
Drop multiple tables in one shot in mysql
...e A has two children B and C. Then we can use the following syntax to drop all tables.
DROP TABLE IF EXISTS B,C,A;
This can be placed in the beginning of the script instead of individually dropping each table.
share
...