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Socket send函数和recv函数详解以及利用select()函数来进行指定时间的阻塞 ...
Socket send函数和recv函数详解以及利用select()函数来进行指定时间的阻塞int send( SOCKET s, const char FAR *buf, int len, int flags ); 不论是客户还是服务器应用程序都用send函数来向TCP连接的...int send( SOCKET s, const char FAR *buf, int len, int flags );
...
How to generate a random alpha-numeric string?
...racters for only 122 bits of entropy. (Not all bits of a "random" UUID are selected randomly.) A randomly chosen alphanumeric string packs more entropy in just 21 characters.
UUIDs are not flexible; they have a standardized structure and layout. This is their chief virtue as well as their main weak...
How can I remove duplicate rows?
...
Assuming no nulls, you GROUP BY the unique columns, and SELECT the MIN (or MAX) RowId as the row to keep. Then, just delete everything that didn't have a row id:
DELETE FROM MyTable
LEFT OUTER JOIN (
SELECT MIN(RowId) as RowId, Col1, Col2, Col3
FROM MyTable
GROUP BY Co...
Convert Rows to columns using 'Pivot' in SQL Server
...9, 3, 87);
If your values are known, then you will hard-code the query:
select *
from
(
select store, week, xCount
from yt
) src
pivot
(
sum(xcount)
for week in ([1], [2], [3])
) piv;
See SQL Demo
Then if you need to generate the week number dynamically, your code will be:
DECLARE @c...
Base64 encoding in SQL Server 2005 T-SQL
...the same:
-- Encode the string "TestData" in Base64 to get "VGVzdERhdGE="
SELECT
CAST(N'' AS XML).value(
'xs:base64Binary(xs:hexBinary(sql:column("bin")))'
, 'VARCHAR(MAX)'
) Base64Encoding
FROM (
SELECT CAST('TestData' AS VARBINARY(MAX)) AS bin
) AS bin_sql_server_t...
SQL/mysql - Select distinct/UNIQUE but return all columns?
...
You're looking for a group by:
select *
from table
group by field1
Which can occasionally be written with a distinct on statement:
select distinct on field1 *
from table
On most platforms, however, neither of the above will work because the behavior o...
How to comment out a block of Python code in Vim
...to allow me to indent certain lines of code (whether those lines have been selected in visual mode, or n lines above/below current cursor position).
...
Split string, convert ToList() in one line
...
var numbers = sNumbers.Split(',').Select(Int32.Parse).ToList();
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Get path of executable
... the predefined OS macros detailed at predef.sourceforge.net/preos.html to select the method is straightforward.
– Clifford
Oct 7 '09 at 15:02
5
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Linux下部署企业级邮件服务器(postfix + dovecot + extmail) - 开源 & Gith...
...er=extmail password=extmail
default_pass_scheme = CRYPT
password_query = SELECT username AS user,password AS password FROM mailbox WHERE username = '%u'
user_query = SELECT maildir, uidnumber AS uid, gidnumber AS gid FROM mailbox WHERE username = '%u'
启动dovecot
service dovecot start
...