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Search found 323 results on 13 pages for 'jian lin'.

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  • In SQL, can we always write an inner join statement as a main query and subquery if we only want to

    - by Jian Lin
    In SQL, can we always write an inner join statement as a main query and subquery or vice versa if we only want to find the intersection? For example, select * from gifts g where g.giftID in (select giftID from sentGifts); can do a join and show the gifts sent in the sentGifts table, but it won't be able to show the sentTime because that is inside the subquery. But if all we care is to find the intersection, without caring what is being displayed, then we can always convert one to the other?

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  • What is the exact rule of jQuery's animate() parameters?

    - by Jian Lin
    jQuery 1.4.2's animate() API spec is .animate( properties, [ duration ], [ easing ], [ callback ] ) but it seems that we can supply duration, callback, and no easing .animate({left: '+= 100'}, 600, doThis) and it will work. But if we supply easing and callback and no duration .animate({left: '+=100'}, 'swing', doThis) then the easing won't be taken into effect. So what exactly is the API supposed to be?

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  • Recreation of DB using "mysql mydb < mydb.sql" is really slow when the table has tens of millions of

    - by Jian Lin
    It seems that a MySQL database that has a table with tens of millions of records will get a big INSERT INTO statement when the following mysqldump some_db > some_db.sql is done to back up the database. (is it 1 insert statement that handles all the records?) So when reconstructing the DB using mysql some_db < some_db.sql then the CPU is hardly busy (about 1.8% usage by the mysql process... I don't see a mysqld either?) and also the hard disk doesn't seem to be too busy... Last time, the whole restore process took 5 hours. Is there a way to make it faster? Such as, when doing mysqldump, can it break the INSERT statement into shorter ones, so that the mysql doesn't need to parse the line so hard when restoring the DB?

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  • In Javascript, is it true that function aliasing works as long as the function being aliased doesn't

    - by Jian Lin
    In Javascript, if we are aliasing a function, such as in: f = g; f = obj.display; obj.f = foo; all the 3 lines above, they will work as long as the function / method on the right hand side doesn't touch this? Since we are passing in all the arguments, the only way it can mess up is when the function / method on the right uses this? Actually, line 1 is probably ok if g is also a property of window? If g is referencing obj.display, then the same problem is there. In line 2, when obj.display touches this, it is to mean the obj, but when f() is invoked, the this is window, so they are different. In line 3, it is the same: when f() is invoked inside of obj's code, then the this is obj, while foo might be using this to refer to window if it were a property of window. (global function). So line 2 can be written as f = function() { obj.display.apply(obj, arguments) } and line 3: obj.f = function() { foo.apply(window, arguments) } Is this the correct method, and are there there other methods besides this?

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  • In CSS, can "#footer #caption" coexist with "#content # caption"?

    - by Jian Lin
    I was going to "nest" the CSS ids like this #content #caption { color: teal } ... #footer #caption { margin: 2em 1em } because that's the way SASS (a CSS generator) can do nesting for... but then in one HTML document, we cannot have two ids with the same name, isn't that true, so the above nesting won't work or won't work well. (esp if document.getElementById() or $('#caption') or $('caption') is needed to select the element). We can use #content #content_caption { color: teal } ... #footer #footer_caption { margin: 2em 1em } but then why 1 more level of nesting? why not just #content_caption { color: teal } ... #footer_caption { margin: 2em 1em } ?

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  • How to install python package without copy everything into lib/site-packages?

    - by Victor Lin
    I want to develop a common python package, I got other packages depends on it. For example: packageA/ packageB/ packageC/ commonPackage/ packageA, packageB and packageC can all be executed directly, but they are all depend on commonPackage. I want to install the commonPackage into lib/site-packages, but I don't want it copys the source code. Instead, I want it creates a commonPackage.pth in lib/site-packages with the path of where the commonPackage at. So that when I modify commonPackage or update it from SVN, I don't need to install it again. Here comes the problem, how can I write the setup.py or use the options of python setup.py install so that it would do what I want?

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  • delete multi-line block of text with internal flag in povray file

    - by Sibo Lin
    I have a pov-ray file, which defines a lot of cylinders and spheres. Sometimes these shapes are defined to have "color@", which makes the povray unrenderable. One solution I've found is to delete the offending cylinders and spheres. So a file that contains this text cylinder { < -0.17623, 0.24511, -0.27947>, < -0.15220, 0.22658, -0.26472>, 0.00716 texture { colorO } } sphere { < -0.00950, 0.00357, 0.00227>, 0.00716 texture { color@ } } cylinder { < -0.00950, 0.00357, 0.00227>, < 0.00327, 0.00169, 0.00108>, 0.00716 texture { color@ } } sphere { < 0.15373, 0.00601, 0.18223>, 0.00716 texture { colorO } } would turn into this text cylinder { < -0.17623, 0.24511, -0.27947>, < -0.15220, 0.22658, -0.26472>, 0.00716 texture { colorO } } sphere { < 0.15373, 0.00601, 0.18223>, 0.00716 texture { colorO } } Is there some way to do this replacement with a shell script? Preferably in tcsh. Thanks!

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  • In Ruby on Rails, routes.rb, if map.something will create something_path and something_url, does map

    - by Jian Lin
    In Ruby on Rails, routes.rb, if we create a "named route" map.something ":a/:b", :controller => 'foobar' it will also create something_path and something_url which are two methods usable in the controller and in the view. Does map.connect create something like that too? Otherwise, isn't map.connect somewhat disadvantaged in this way? I checked that connect_path and connect_url both aren't created automatically.

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  • Why does it matter that in Javascript, scope is function-level, not block-level?

    - by Jian Lin
    In the question http://stackoverflow.com/questions/1451009/javascript-infamous-loop-problem the accepted answer from Christoph's says that JavaScript's scopes are function-level, not block-level What if Javascript's scopes are block-level, then would the Infamous Loop problem still occur? But will there be a different (or easier way) to fix it? Is it as opposed to other languages, where using a { would start a new scope?

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  • Expanding Git SHA1 information into a checkin without archiving?

    - by Tim Lin
    Is there a way to include git commit hashes inside a file everytime I commit? I can only find out how to do this during archiving but I haven't been able to find out how to do this for every commit. I'm doing scientific programming with git as revision control, so this kind of functionality would be very helpful for reproducibility reasons (i.e., have the git hash automatically included in all result files and figures).

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  • What are some useful SQL statements that should be known by all developers who may touch the Back en

    - by Jian Lin
    What are some useful SQL statements that should be known by all developers who may touch the Back end side of the project? (Update: just like in algorithm, we know there are sorting problems, shuffling problems, and we know some solutions to them. This question is aiming at the same thing). For example, ones I can think of are: Get a list of Employees and their boss. Or one with the employee's salary greater than the boss. (Self-join) Get a list of the most popular Classes registered by students, from the greatest number to the smallest. (Count, group by, order by) Get a list of Classes that are not registered by any students. (Outer join and check whether the match is NULL, or by Get from Classes table, all ClassIDs which are NOT IN (a subquery to get all ClassIDs from the Registrations table)) Are there some SQL statements that should be under the sleeve of all developers that might touch back end data?

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  • Can a binary tree or tree be always represented in a Database table as 1 table and self-referencing?

    - by Jian Lin
    I didn't feel this rule before, but it seems that a binary tree or any tree (each node can have many children but children cannot point back to any parent), then this data structure can be represented as 1 table in a database, with each row having an ID for itself and a parentID that points back to the parent node. That is in fact the classical Employee - Manager diagram: one boss can have many people under him... and each person under him can have n people under him, etc. This is a tree structure and is represented in database books as a common example as a single table Employee.

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  • In HAML on Ruby on Rails, how to use the :sass filter?

    - by Jian Lin
    If using HAML on Ruby on Rails, then :sass #someDiv border: 3px dashed orange won't have any <style> tag around them. and then :css :sass #someDiv border: 3px dashed orange won't kick on the :sass filter, but :css :sass #someDiv border: 3px dashed orange will kick on the :sass filter, but it is outside of the <style> tag. So how can the :sass filter be used?

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  • Using Ruby on Rails, can a polymorphic database be created in a few steps (with polymorphic associat

    - by Jian Lin
    I thought it could be created in a few steps but it can't yet: rails poly cd poly ruby script/generate scaffold animal name:string obj_type:string obj_id:integer rake:migrate ruby script/generate scaffold human name:string passportNumber:string rake:migrate ruby script/generate scaffold dog name:string registrationNumber:string rake:migrate and now change app/models/animal.rb to: class Animal < ActiveRecord::Base belongs_to :obj, :polymorphic => true end and run ruby script/server and go to http://localhost:3000 I thought on the server then if I create an Michael, Human, J123456 and then Woofie, Dog, L23456 then the database will have entries in the Dogs table and "Humen" or "Humans" table as well as in the Animals table? But only the Animals table has records, Dogs and "Humen" do not for some reason. Is there some steps missing?

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  • In MVC framworks (such as Ruby on Rails), does usually Model spell as singular and controller and vi

    - by Jian Lin
    I usually see Ruby on Rails books using script/generate model Story name:string link:string which is a singular Story, while when it is controller script/generate controller Stories index then the Story now is Stories, which is plural. Is this a standard on Ruby on Rails? Is it true in other MVC frameworks too, like CakePHP, Symfony, Django, or TurboGears? I see that in the book Rails Space, the controller is also called User, which is the same as the model name, and it is the only exception I see. Update: also, when scaffold is done on Ruby on Rails, then automatically, the model is singular and the controller and view are both plural.

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  • Problem with notification bar in fullscreen app

    - by Mathias Lin
    I run an app in fullscreen mode where fullscreen is defined as a theme in xml for the entire app. <style name="AskTingTingTheme" parent="android:Theme"> <item name="android:windowNoTitle">true</item> <item name="android:windowFullscreen">true</item> <item name="android:windowBackground">@null</item> </style> Generally it works ok, but there are some issues in some cases: 1) when I open the search dialog via search button - Screenshot: http://tinyurl.com/3xzadft 2) when I open spinner widgets that are very long and fill the screen (so that the list is usually scrollable) - Screenshot: http://tinyurl.com/39q5ya2 The problem is that when I open the search dialog or spinner widget, the system notification bar occurs for a few millisecs and then scrolls off the screen again. Please see the screenshots linked above. I'm currently on 2.2 with NexusOne, but same thing happened on 2.1update1 (esp. case 2) as well before.

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  • What are some useful SQL statements / usage patterns that should be known by all developers who may

    - by Jian Lin
    What are some useful SQL statements that should be known by all developers who may touch the Back end side of the project? (Update: just like in algorithm, we know there are sorting problems, shuffling problems, and we know some solutions to them. This question is aiming at the same thing). For example, ones I can think of are: Get a list of Employees and their boss. Or one with the employee's salary greater than the boss. (Self-join) Get a list of the most popular Classes registered by students, from the greatest number to the smallest. (Count, group by, order by) Get a list of Classes that are not registered by any students. (Outer join and check whether the match is NULL, or by Get from Classes table, all ClassIDs which are NOT IN (a subquery to get all ClassIDs from the Registrations table)) Are there some SQL statements that should be under the sleeve of all developers that might touch back end data?

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  • In SQL, what does Group By mean without Count(*), or Sum(), Max(), avg(), ..., and what are some use

    - by Jian Lin
    In SQL, if we use Group By without Count(*) or Sum(), etc, then the result is as follows: mysql> select * from sentGifts; +--------+------------+--------+------+---------------------+--------+ | sentID | whenSent | fromID | toID | trytryWhen | giftID | +--------+------------+--------+------+---------------------+--------+ | 1 | 2010-04-24 | 123 | 456 | 2010-04-24 01:52:20 | 100 | | 2 | 2010-04-24 | 123 | 4568 | 2010-04-24 01:56:04 | 100 | | 3 | 2010-04-24 | 123 | NULL | NULL | 1 | | 4 | 2010-04-24 | NULL | 111 | 2010-04-24 03:10:42 | 2 | | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | 6 | | 6 | 2010-04-24 | 11 | 222 | 2010-04-24 03:54:49 | 6 | | 7 | 2010-04-24 | 1 | 2 | 2010-04-24 03:58:45 | 6 | +--------+------------+--------+------+---------------------+--------+ 7 rows in set (0.00 sec) mysql> select *, count(*) from sentGifts group by whenSent; +--------+------------+--------+------+---------------------+--------+----------+ | sentID | whenSent | fromID | toID | trytryWhen | giftID | count(*) | +--------+------------+--------+------+---------------------+--------+----------+ | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | 6 | 1 | | 1 | 2010-04-24 | 123 | 456 | 2010-04-24 01:52:20 | 100 | 6 | +--------+------------+--------+------+---------------------+--------+----------+ 2 rows in set (0.00 sec) mysql> select * from sentGifts group by whenSent; +--------+------------+--------+------+---------------------+--------+ | sentID | whenSent | fromID | toID | trytryWhen | giftID | +--------+------------+--------+------+---------------------+--------+ | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | 6 | | 1 | 2010-04-24 | 123 | 456 | 2010-04-24 01:52:20 | 100 | +--------+------------+--------+------+---------------------+--------+ 2 rows in set (0.00 sec) Only 1 row is returned per "group". What does it mean when there is no "Count(*)", etc when using "Group By", and what are it uses? thanks.

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  • Do we need Record Level Locking when we already have Transaction for online ordering? (of concert ti

    - by Jian Lin
    For online ordering of concert seat or airline ticket, do we need Record Level Locking or is Transaction good enough? For concert ticket (say, seat Number 20B), or airline ticket (even with overbooking, the limit is 210, for example), I think the website cannot lock any record or begin transaction when showing the ticket purchase screen. But after the user clicks "Confirm Purchase", then the server should Begin a Transaction, Purchase Seat Number 20B, and try to Commit. If another user already bought Seat 20B in a previous transaction, then it is the "Commit" part that the current transaction will fail? So... we don't need Record Level Locking? Do Transactions always go serialized (one after another), so that's why we can know for sure there is no "race condition"? In what situation is Record Level Locking needed then?

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