大约有 42,000 项符合查询结果（耗时：0.0328秒） [XML]
Is there any difference between GROUP BY and DISTINCT
...CT and distinct by UNION cause an oracle error, but GROUP BY worked; I was selecting only 1 column from a view and not using any aggregation; I'm still baffled why it required it, but it does confirm there is some difference in the execution. As others point out, it also lets you GROUP BY columns no...
Get names of all files from a folder with Ruby
...ng subdirectories and ".", ".." dotted folders:
Dir.entries("your/folder").select { |f| File.file? File.join("your/folder", f) }
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Jump to matching XML tags in Vim
...n do this without additional plugins:
place cursor on the tag
vat - will select the (outer) tag and place cursor on the end
once you've got your selection you can toggle between the top and bottom with o (update based on Michael Gruber's note)
c - change or, y - copy or, escape for leaving visual ...
Get top n records for each group of grouped results
...ould need to specify the group number and add queries for each group:
(
select *
from mytable
where `group` = 1
order by age desc
LIMIT 2
)
UNION ALL
(
select *
from mytable
where `group` = 2
order by age desc
LIMIT 2
)
There are a variety of ways to do this, see this articl...
How do you connect to multiple MySQL databases on a single webpage?
...d);
$dbh2 = mysql_connect($hostname, $username, $password, true);
mysql_select_db('database1', $dbh1);
mysql_select_db('database2', $dbh2);
Then to query database 1 pass the first link identifier:
mysql_query('select * from tablename', $dbh1);
and for database 2 pass the second:
mysql_query...
jQuery or CSS selector to select all IDs that start with some string [duplicate]
How can I select all elements whose id starts with "player_"?
4 Answers
4
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Any way to select without causing locking in MySQL?
...s/22-mysql-with-nolock.aspx
in MS SQL Server you would do the following:
SELECT * FROM TABLE_NAME WITH (nolock)
and the MYSQL equivalent is
SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ;
SELECT * FROM TABLE_NAME ;
SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ ;
EDIT
Mic...
How can I remove the first line of a text file using bash/sed script?
... of magnitude. I'm testing it on a file of 500,000K lines (no more than 50 chars per line). However, I then realized I was using the FreeBSD version of tail (which comes with OS X by default). When I switched to GNU tail, the tail call was 10 times faster than the sed call (and the GNU sed call, too...
select into in mysql
...
Use the CREATE TABLE SELECT syntax.
http://dev.mysql.com/doc/refman/5.0/en/create-table-select.html
CREATE TABLE new_tbl SELECT * FROM orig_tbl;
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How can I remove or replace SVG content?
...
Here is the solution:
d3.select("svg").remove();
This is a remove function provided by D3.js.
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