大约有 42,000 项符合查询结果（耗时：0.0519秒） [XML]
JPA EntityManager: Why use persist() over merge()?
...t to the entity manager.
merge:
Find an attached object with the same id and update it.
If exists update and return the already attached object.
If doesn't exist insert the new register to the database.
persist() efficiency:
It could be more efficient for inserting a new register to a data...
What does SQL clause “GROUP BY 1” mean?
...
SELECT account_id, open_emp_id
^^^^ ^^^^
1 2
FROM account
GROUP BY 1;
In above query GROUP BY 1 refers to the first column in select statement which is
account_id.
You also can specify in ORDER BY....
In a django model custom save() method, how should you identify a new object?
...t self._state is not a private instance variable, but named that way to avoid conflicts, checking self._state.adding is now the preferable way to check.
self.pk is None:
returns True within a new Model object, unless the object has a UUIDField as its primary_key.
The corner case you might have...
How to set the text color of TextView in code?
In XML, we can set a text color by the textColor attribute, like android:textColor="#FF0000" . But how do I change it by coding?
...
How can I use optional parameters in a T-SQL stored procedure?
...cedure that will handle this? Let's say I have a table with four fields: ID, FirstName, LastName and Title. I could do something like this:
...
Why do access tokens expire?
...
This is very much implementation specific, but the general idea is to allow providers to issue short term access tokens with long term refresh tokens. Why?
Many providers support bearer tokens which are very weak security-wise. By making them short-lived and requiring refresh, they...
What is the colon operator in Ruby?
...bols have the distinct feature that any two symbols named the same will be identical:
"foo".equal? "foo" # false
:foo.equal? :foo # true
This makes comparing two symbols really fast (since only a pointer comparison is involved, as opposed to comparing all the characters like you would in a st...
Role/Purpose of ContextLoaderListener in Spring?
...r is that it creates a WebApplicationContext and WebApplicationContext provides access to the ServletContext via ServletContextAware beans and the getServletContext method.
share
|
improve this answ...
What's “requestCode” used for on PendingIntent?
...ance later on (for cancelling, etc).
Yes, my guess is the alarms will override each other. I would keep the request codes unique.
share
|
improve this answer
|
follow
...
Can I underline text in an Android layout?
How can I define underlined text in an Android layout xml file?
25 Answers
25
...