大约有 3,558 项符合查询结果（耗时：0.0214秒） [XML]
Does MySQL ignore null values on unique constraints?
...
Yes, MySQL allows multiple NULLs in a column with a unique constraint.
CREATE TABLE table1 (x INT NULL UNIQUE);
INSERT table1 VALUES (1);
INSERT table1 VALUES (1); -- Duplicate entry '1' for key 'x'
INSERT table1 VALUES (NULL);
I...
How can I access the MySQL command line with XAMPP for Windows?
How can I access the MySQL command line with XAMPP for Windows?
15 Answers
15
...
Is PowerShell ready to replace my Cygwin shell on Windows? [closed]
... the whole provider model.
You can treat the registry, certificate store, SQL Server, Internet Explorer's RSS cache, etc. as an object space navigable by the same cmdlets as the filesystem.
PowerShell is definitely the way forward on Windows. Microsoft has made it part of their requirements for...
Using Transactions or SaveChanges(false) and AcceptAllChanges()?
...re using EF6 (Entity Framework 6+), this has changed for database calls to SQL.
See: http://msdn.microsoft.com/en-us/data/dn456843.aspx
use context.Database.BeginTransaction.
From MSDN:
using (var context = new BloggingContext())
{
using (var dbContextTransaction = context.Database.BeginTr...
Is there a naming convention for MySQL?
...ul for those who will come here later: launchbylunch.com/posts/2014/Feb/16/sql-naming-conventions/…
– Enissay
Feb 2 '16 at 14:59
1
...
Java to Clojure rewrite
...ramework that builds on top of Ring.
Korma - a very nice DSL for accessing SQL databases.
share
|
improve this answer
|
follow
|
...
Storing Image Data for offline web application (client-side storage database)
...ta"
http://www.aaron-powell.com/web/indexeddb-storage
Note: FireFox uses SQLlite for the NOSQL IndexedDB. That might be the reason for the slow performance. (blobs stored separately)
Note: Microsoft IE uses the extensible storage engine:
http://en.wikipedia.org/wiki/Extensible_Storage_Engine
No...
In Java, when should I create a checked exception, and when should it be a runtime exception? [dupli
...e, if I'm passing up from my persistence layer, I would like to convert an SQL exception to a persistence exception, since the next layer up shouldn't care that I'm persisting to a SQL database, but will want to know if something could not be persisted. Another technique I use is to create a simple...
Chaining multiple filter() in Django, is this a bug?
...
As you can see in the generated SQL statements the difference is not the "OR" as some may suspect. It is how the WHERE and JOIN is placed.
Example1 (same joined table) :
(example from https://docs.djangoproject.com/en/dev/topics/db/queries/#spanning-mult...
Good example of livelock?
...ple is two competing processes live locking in an attempt to correct for a SQL server deadlock, with each process using the same wait-retry algorithm for retrying. While it's the luck of timing, I have seen this happen on separate machines with similar performance characteristics in response to a me...