大约有 41,000 项符合查询结果（耗时：0.0517秒） [XML]
What's the main difference between int.Parse() and Convert.ToInt32
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Yeah, Convert.ToInt32(char) will actually return (int)value, which will turn '1' into 49. Not generally the intended functionality.
– Dale K
Oct 24 '13 at 18:28
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Effective method to hide email from spam bots
...'@'), indexOf('mailto:'), etc. The parsing thread would receive only +-200 chars around the match which would allow so complex parsing that it would 'appear' to be infinite in terms of parsing power.
– Jani Hyytiäinen
Feb 28 '15 at 8:33
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Most efficient way to concatenate strings?
...gt; and other input types, with and without separators of different types (Char, String), but here I show the simple case of concatenating all strings in an array into a single string, with no separator. Latest version here is developed and unit-tested on C# 7 and .NET 4.7.
There are two keys to h...
What is the most efficient/elegant way to parse a flat table into a tree?
...port recursive queries in standard syntax.
WITH RECURSIVE MyTree AS (
SELECT * FROM MyTable WHERE ParentId IS NULL
UNION ALL
SELECT m.* FROM MyTABLE AS m JOIN MyTree AS t ON m.ParentId = t.Id
)
SELECT * FROM MyTree;
I tested recursive queries in MySQL 8.0 in my presentation Recursive ...
How to return result of a SELECT inside a function in PostgreSQL?
... bigint
, ratio bigint) AS
$func$
BEGIN
RETURN QUERY
SELECT t.txt
, count(*) AS cnt -- column alias only visible inside
, (count(*) * 100) / _max_tokens -- I added brackets
FROM (
SELECT t.txt
FROM token t
WHERE t.charty...
INSERT INTO … SELECT FROM … ON DUPLICATE KEY UPDATE
...olumns named in the INSERT INTO clause, and the second part references the SELECT columns.
INSERT INTO lee(exp_id, created_by, location, animal, starttime, endtime, entct,
inact, inadur, inadist,
smlct, smldur, smldist,
larct, lardur, lardist,
...
How to count occurrences of a column value efficiently in SQL?
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This should work:
SELECT age, count(age)
FROM Students
GROUP by age
If you need the id as well you could include the above as a sub query like so:
SELECT S.id, S.age, C.cnt
FROM Students S
INNER JOIN (SELECT age, count(age) a...
How to subtract 30 days from the current datetime in mysql?
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SELECT * FROM table
WHERE exec_datetime BETWEEN DATE_SUB(NOW(), INTERVAL 30 DAY) AND NOW();
http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_date-add
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Return rows in random order [duplicate]
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SELECT * FROM table
ORDER BY NEWID()
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How to use Oracle ORDER BY and ROWNUM correctly?
...n Oracle.
If you want a version that works in both servers, you can use:
select ril.*
from (select ril.*, row_number() over (order by t_stamp desc) as seqnum
from raceway_input_labo ril
) ril
where seqnum = 1
The outer * will return "1" in the last column. You would need to list the ...