大约有 19,000 项符合查询结果（耗时：0.0281秒） [XML]
How do I modify a MySQL column to allow NULL?
...
This did not work for me! The column did not change. Maybe because I had a constraint to another table where the column was used (when not null).
– Rocologo
Dec 18 '16 at 10:09
...
Alter Table Add Column Syntax
I'm trying to programmatically add an identity column to a table Employees. Not sure what I'm doing wrong with my syntax.
4...
Difference between this and self in self-type annotations?
...
All three forms are valid, and have the effect that B is assumed as the type of this in class A.
The first two variants
trait A { self: B => ... }
trait A { foo: B => ... }
introduce self (respectively, foo) as an alias for this in trait...
Is there any difference between a GUID and a UUID?
...hrown around, and I was wondering if there are any differences between a GUID and a UUID?
6 Answers
...
Differences between utf8 and latin1
...AR and decode/encode in the business tier yourself, but this is hacky. Consider asking a new question, maybe there are better ways.
– BalusC
Jun 12 '12 at 18:57
...
Python: Using .format() on a Unicode-escaped string
..."{}".format(u"\u2265") will throw an exception.
– Hylidan
Feb 18 '15 at 0:51
2
what a simple thin...
Event handling for iOS - how hitTest:withEvent: and pointInside:withEvent: are related?
...ile most apple documents are very well written, I think ' Event Handling Guide for iOS ' is an exception. It's hard for me to clearly understand what's been described there.
...
differences between 2 JUnit Assert classes
...it.framework.Assert and org.junit.Assert. It is, however, probably a good idea to stick to the org.junit.Assert class since it is newer , slightly rewritten and probably meant as a replacement.
– Glenn Bech
Nov 30 '15 at 9:51
...
How do I convert an interval into a number of hours with postgres?
... SELECT EXTRACT(epoch FROM my_interval/3600) (interval has native 'divide integer' support, result is interval, and extract result is integer, not float). So. Autocast/Floor done.
– Offenso
Aug 12 '15 at 13:24
...
How can I define a composite primary key in SQL?
...te primary key. It is defined as follows:
CREATE TABLE voting (
QuestionID NUMERIC,
MemberID NUMERIC,
PRIMARY KEY (QuestionID, MemberID)
);
The pair (QuestionID,MemberID) must then be unique for the table and neither value can be NULL. If you do a query like this:
SELECT * FROM voting WHER...