大约有 42,000 项符合查询结果（耗时：0.0590秒） [XML]
In SQL, what's the difference between count(column) and count(*)?
...s not
[edit] added this code so that people can run it
create table #bla(id int,id2 int)
insert #bla values(null,null)
insert #bla values(1,null)
insert #bla values(null,1)
insert #bla values(1,null)
insert #bla values(null,1)
insert #bla values(1,null)
insert #bla values(null,null)
select count(...
Want to find records with no associated records in Rails
Consider a simple association...
8 Answers
8
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Using IQueryable with Linq
... user's perspective, is that, when you use IQueryable<T> (with a provider that supports things correctly), you can save a lot of resources.
For example, if you're working against a remote database, with many ORM systems, you have the option of fetching data from a table in two ways, one which...
android.view.InflateException: Binary XML file: Error inflating class fragment
I have a very frustrating error that I cannot explain. I created an Android application that uses Android AppCompat to make it compatible with older versions. Here is my main activity layout file:
...
How to remove multiple indexes from a list at the same time? [duplicate]
... Looping over indices backwards. Genius! I was here dreaming up some ridiculous situation of decrementing indices as I went along, when this was so much more elegant!
– Neil
Apr 20 '15 at 22:37
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Escape quote in web.config connection string
... file so you should use XML escaping.
connectionString="Server=dbsrv;User ID=myDbUser;Password=somepass&quot;word"
See this forum thread.
Update:
&quot; should work, but as it doesn't, have you tried some of the other string escape sequences for .NET? \" and ""?
Update 2:
Try single q...
Heroku 'Permission denied (publickey) fatal: Could not read from remote repository' woes
...e it could not find that key on my computer. The solution?
ssh-add ~/.ssh/id_rsa
#and, to confirm it's been added to the known list of keys
ssh-add -l
I would like to give credit to https://help.github.com/articles/error-permission-denied-publickey for being a good reference.
...
SQL Server add auto increment primary key to existing table
...ting table which is already populated with 150000 records. I have added an Id column (which is currently null).
15 Answers
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Rails :include vs. :joins
...ails. Here is an explaination of what I understood (with examples :))
Consider this scenario:
A User has_many comments and a comment belongs_to a User.
The User model has the following attributes: Name(string), Age(integer). The Comment model has the following attributes:Content, user_id. For a ...
MySQL: Quick breakdown of the types of joins [duplicate]
...hell, the comma separated example you gave of
SELECT * FROM a, b WHERE b.id = a.beeId AND ...
is selecting every record from tables a and b with the commas separating the tables, this can be used also in columns like
SELECT a.beeName,b.* FROM a, b WHERE b.id = a.beeId AND ...
It is then getti...