大约有 44,000 项符合查询结果（耗时：0.0331秒） [XML]
Why do we need fibers
... each. Think about it: normally all the Enumerable methods, including map, select, include?, inject, and so on, all work on the elements yielded by each. But what if an object has other iterators other than each?
irb(main):001:0> "Hello".chars.select { |c| c =~ /[A-Z]/ }
=> ["H"]
irb(main):00...
IEnumerable to string [duplicate]
...urer sequence, rather than a cast. Something like Enumerable.Range(65, 26).Select(i => (char)i);, this should avoid the chance for an optimized shortcut.
– Jodrell
Oct 28 '13 at 9:39
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ORA-00979 not a group by expression
...
You must put all columns of the SELECT in the GROUP BY or use functions on them which compress the results to a single value (like MIN, MAX or SUM).
A simple example to understand why this happens: Imagine you have a database like this:
FOO BAR
0 A
0 ...
Natural Sort Order in C#
...haNumeric<T>(this IEnumerable<T> source, Func<T, string> selector)
{
int max = source
.SelectMany(i => Regex.Matches(selector(i), @"\d+").Cast<Match>().Select(m => (int?)m.Value.Length))
.Max() ?? 0;
return source.OrderBy(i => Regex.Replace(s...
How to read the output from git diff?
...
On my mac:
info diff then select: Output formats -> Context -> Unified format -> Detailed Unified :
Or online man diff on gnu following the same path to the same section:
File: diff.info, Node: Detailed
Unified, Next: Example Unified...
How do I concatenate const/literal strings in C?
...hing
const char *qry = // include comments in a string
" SELECT * " // get all fields
" FROM " SCHEMA "." TABLE /* the table */
" WHERE x = 1 " /* the filter */
;
...
MySQL一次主从数据不一致的问题解决过程 - 数据库(内核) - 清泛网 - 专注C/...
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pt-table-checksum校验数据一致性。
从库mysql操作
GRANT SELECT,PROCESS, SUPER, REPLICATION SLAVE ON *.* TO 'checksums'@'192.168.1.100' IDENTIFIED BY 'slavecheck'; flush privileges;
主库mysql操作
GRANT SELECT, PROCESS, SUPER, REPLICATION SLAVE ON *.* TO 'checksums'@'19...
How do I split a string so I can access item x?
...0,
PATINDEX('%|%', @products))
SELECT @individual
SET @products = SUBSTRING(@products,
LEN(@individual + '|') + 1,
LEN(@products))
END
ELSE
BEGIN
SET @individu...
SQL query to group by day
...dateadd(DAY,0, datediff(day,0, created)) return '2009-11-02 00:00:00.000'
select sum(amount) as total, dateadd(DAY,0, datediff(day,0, created)) as created
from sales
group by dateadd(DAY,0, datediff(day,0, created))
share
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Storing Data in MySQL as JSON
... statement, including WHERE, ORDER BY, and GROUP BY clauses. This includes SELECT, UPDATE, DELETE, CREATE TABLE, and other SQL statements. The left hand side must be a JSON column identifier (and not an alias). The right hand side is a quoted JSON path expression which is evaluated against the JSON ...