大约有 47,000 项符合查询结果（耗时：0.0609秒） [XML]
What is in your Mathematica tool bag? [closed]
...pplication of Reap and Sow which mimics/extends the behavior of GatherBy:
SelectEquivalents[x_List,f_:Identity, g_:Identity, h_:(#2&)]:=
Reap[Sow[g[#],{f[#]}]&/@x, _, h][[2]];
This allows me to group lists by any criteria and transform them in the process. The way it works is that a c...
Cannot issue data manipulation statements with executeQuery()
...() to issue data manipulation statements. executeQuery() is only meant for SELECT queries (i.e. queries that return a result set).
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Hidden Features of Visual Studio (2005-2010)?
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Make a selection with ALT pressed - selects a square of text instead of whole lines.
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answered Sep 19 ...
How to import an excel file in to a MySQL database
...r Excel table into the sales table of a MySQL database named mydatabase.
Select the relevant cells:
Paste into Mr. Data Converter and select the output as MySQL:
Change the table name and column definitions to fit your requirements in the generated output:
CREATE TABLE sales (
id INT NOT N...
mysql error 1364 Field doesn't have a default values
...nt tool, such as phpMyAdmin: -- verified that the mode was previously set select @@GLOBAL.sql_mode; -- UPDATE MODE SET @@global.sql_mode= 'YOUR_VALUE';
– anasanjaria
Dec 4 '13 at 18:17
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How to find the port for MS SQL Server 2008?
...nfiguration -> Client Protocols -> TCP/IP
double click ( Right click select Properties ) on TCP/IP.
You will find Default Port 1433.
Depending on connection, the port number may vary.
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MySQL: Order by field size/length
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SELECT * FROM TEST ORDER BY LENGTH(description) DESC;
The LENGTH function gives the length of string in bytes. If you want to count (multi-byte) characters, use the CHAR_LENGTH function instead:
SELECT * FROM TEST ORDER BY...
Why does PostgreSQL perform sequential scan on indexed column?
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If the SELECT returns more than approximately 5-10% of all rows in the table, a sequential scan is much faster than an index scan.
This is because an index scan requires several IO operations for each row (look up the row in the ...
What is the difference between a pseudo-class and a pseudo-element in CSS?
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The CSS 3 selector recommendation is pretty clear about both, but I'll try to show the differences anyway.
Pseudo-classes
Official description
The pseudo-class concept is introduced to permit selection based on information that l...
What do querySelectorAll and getElementsBy* methods return?
...sByClassName (and similar functions like getElementsByTagName and querySelectorAll ) work the same as getElementById or do they return an array of elements?
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