大约有 40,000 项符合查询结果（耗时：0.0499秒） [XML]
static const vs #define
... The pro and cons are mixed up, I would be very like to see a comparison table.
– Unknown123
Apr 25 '19 at 3:49
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The multi-part identifier could not be bound
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FROM (a, b) LEFT JOIN dkcd ON …
WHERE …
that is, the combination of tables a and b is joined with the table dkcd. In fact, what's happening is
SELECT
…
FROM a, (b LEFT JOIN dkcd ON …)
WHERE …
that is, as you may already have understood, dkcd is joined specifically against b and onl...
LEFT OUTER JOIN in LINQ
...nificantly more readable left outer join can be written as such:
from maintable in Repo.T_Whatever
from xxx in Repo.T_ANY_TABLE.Where(join condition).DefaultIfEmpty()
If you omit the DefaultIfEmpty() you will have an inner join.
Take the accepted answer:
from c in categories
join p in pr...
spring boot default H2 jdbc connection (and H2 console)
...erties and start with mvn spring:run. I can see hibernate JPA creating the tables but if I try to access the h2 console at the URL below the database has no tables.
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Rails migrations: self.up and self.down versus change
... you rollback? Of course it's remove_column. What is the inverse of create_table? It's drop_table. So in these cases rails know how to rollback and define a down method is superfluous (you can see in the documentation the methods currently supported from the change method).
But pay attention becaus...
What's the fastest algorithm for sorting a linked list?
... the interesting part is to investigate whether you can sort it in-place, stably, its worst-case behavior and so on.
Simon Tatham, of Putty fame, explains how to sort a linked list with merge sort. He concludes with the following comments:
Like any self-respecting sort algorithm, this has runn...
to drawRect or not to drawRect (when should one use drawRect/Core Graphics vs subviews/images and wh
...it would be more complicated.
The general workflow should be to build the tableviews with subviews. Use Instruments to measure the frame rate on the oldest hardware your app will support. If you can't get 60fps, drop down to CoreGraphics. When you've done this for a while, you get a sense for when ...
psql - save results of command to a file
I'm using psql's \dt to list all tables in a database and I need to save the results.
10 Answers
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How to do a LIKE query in Arel and Rails?
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This is how you perform a like query in arel:
users = User.arel_table
User.where(users[:name].matches("%#{user_name}%"))
PS:
users = User.arel_table
query_string = "%#{params[query]}%"
param_matches_string = ->(param){
users[param].matches(query_string)
}
User.where(param_matc...
Status bar and navigation bar appear over my view's bounds in iOS 7
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Also note that when your main view is a UITableView the viewDidLayoutSubviews will get called on each scroll. Your UITableView will be scaled down until its height is 15px. Add a flag to only run this code once. ;)
– Thomas Johannesmeyer
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