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Does MySQL ignore null values on unique constraints?
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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
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互联网造车运动 - 资讯 - 清泛网 - 专注C/C++及内核技术
...其核心技术在于自主设计的底盘和电池控制系统，从最初使用莲花Elise底盘到自主设计，这期间历时长达十年之久，此外，特斯拉还学习了丰田的质量控制和问题追溯体系，还有奔驰的测试流程，传统汽车企业的支持是特斯拉成...
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
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Java to Clojure rewrite
...ramework that builds on top of Ring.
Korma - a very nice DSL for accessing SQL databases.
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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...
区块链技术到底是什么鬼，为何被疯炒？ - 资讯 - 清泛网 - 专注C/C++及内核技术
...金融机构共同建立了R3CEV联盟,旨在推动制定适合金融机构使用的区块链技术标准,推动技术落地。
区块链很火，但是真正了解它的人有多少呢？
一、什么是区块链？
说到区块链，就不得不说比特币。
2008年底，比特币之父中...
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...