NULL/0 - PostgreSQL Database

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by: Agoston Bejo | last post by:

I want to enforce such a constraint on a column that would ensure that the values be all unique, but this wouldn't apply to NULL values. (I.e. there may be more than one NULL value in the column.) How can I achieve this? I suppose I would get the most-hated "table/view is changing, trigger/function may not see it" error if I tried to write a trigger that checks the uniqueness of non-null values upon insert/update.

Oracle Database

2129

Null - between the ears (long)

by: iStrain | last post by:

Hiya. I'm _sure_ this is an FAQ, but Googling hasn't produced the answer in a way I can make sense out of. I know I should get this, but so far no way... I'm creating tables and doing queries in Perl, and Nulls have started to bother me greatly. The first issue is, as far as I understand it, a column should be NOT NULL if it is necessary (required) data. Now, if a column doesn't have to be NOT NULL; that is, it's not _required_ data,...

MySQL Database

4256

Null in subquery returns no records

by: Mike MacSween | last post by:

This as the row source for a combo: SELECT qryRole.RoleID, qryRole.Role FROM qryRole WHERE (((qryRole.RoleID) Not In (SELECT RoleID FROM qryRoleEvent INNER JOIN qryEvent ON qryRoleEvent.EventID = qryEvent.EventID WHERE ProdID = Forms!frmProductions!ProdID))) ORDER BY qryRole.Role; If there is just one RoleID with a null value in the subquery then the main

Microsoft Access / VBA

7661

struct's first member and the NULL pointer

by: sathyashrayan | last post by:

The standard confirms that the following initialization of a struct struct node { --- --- } struct node var = {NULL};

by: junky_fellow | last post by:

Can 0x0 be a valid virtual address in the address space of an application ? If it is valid, then the location pointed by a NULL pointer is also valid and application should not receive "SIGSEGV" ( i am talking of unix machine ) while trying to read that location. Then how can i distinguish between a NULL pointer and an invalid location ? Is this essential that NULL pointer should not point to any of the location in the virtual address...

C / C++

3768

Definition of NULL

by: Jason Curl | last post by:

I've been reading this newsgroup for some time and now I am thoroughly confused over what NULL means. I've read a NULL pointer is zero (or zero typecast as a void pointer), others say it's compiler dependent (and that NULL might be anything, but it is always NULL). The source snippet is below. The question is: - When I use calloc to allocate a block of memory, preinitialising it to zero, is this equivalent (and portable C) to...

C / C++

24722

How to Serialize 'null'?

by: David Sworder | last post by:

Hi, I've created a UserControl-derived class called MyUserControl that is able to persist and subsequently reload its state. It exposes two methods as follows: public void Serialize(Stream s); public void Deserialize(Stream s); Within the MyUserControl class, there is a field of type MyInnerClass

C# / C Sharp

3943

NULL with representation other then all bits 0

by: yossi.kreinin | last post by:

Hi! There is a system where 0x0 is a valid address, but 0xffffffff isn't. How can null pointers be treated by a compiler (besides the typical "solution" of still using 0x0 for "null")? - AFAIK C allows "null pointers" to be represented differently then "all bits 0". Is this correct? - AFAIK I can't `#define NULL 0x10000' since `void* p=0;' should work just like `void* p=NULL'. Is this correct?

C / C++

5405

HttpContext.Current is Null in PreSendRequestHeaders

by: Aaron Morton | last post by:

I'm working on a IHttpModule that handles the PreSendRequestHeaders event from the HttpApplication, if the event is raised after EndRequest then HttpContext.Current is null. If it is raised before EndRequest (by turning response buffering off) then HttpContext.Current is set. To repo add the following to Global.asax protected void Application_PreSendRequestHeaders(object sender, EventArgs e) {...

ASP.NET

3682

Equivalent malloc with calloc

by: lovecreatesbea... | last post by:

Do you prefer malloc or calloc? p = malloc(size); Which of the following two is right to get same storage same as the above call? p = calloc(1, size); p = calloc(size, 1);

C / C++

9957

Maximizing Business Potential: The Nexus of Website Design and Digital Marketing

by: jinu1996 | last post by:

In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...

Online Marketing

9905

The easy way to turn off automatic updates for Windows 10/11

by: Hystou | last post by:

Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...

Windows Server

9775

Discussion: How does Zigbee compare with other wireless protocols in smart home applications?

by: tracyyun | last post by:

Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...

General

8780

AI Job Threat for Devs

by: agi2029 | last post by:

Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...

Career Advice

7332

Access Europe - Using VBA to create a class based on a table - Wed 1 May

by: isladogs | last post by:

The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...

Microsoft Access / VBA

6609

Couldn’t get equations in html when convert word .docx file to html file in C#.

by: conductexam | last post by:

I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one. At the time of converting from word file to html my equations which are in the word document file was convert into image. Globals.ThisAddIn.Application.ActiveDocument.Select();...

C# / C Sharp

5373

Windows Forms - .Net 8.0

by: adsilva | last post by:

A Windows Forms form does not have the event Unload, like VB6. What one acts like?

Visual Basic .NET

3881

transfer the data from one system to another through ip address

by: 6302768590 | last post by:

Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system

C# / C Sharp

3456

How to add payments to a PHP MySQL app.

by: muto222 | last post by:

How can i add a mobile payment intergratation into php mysql website.

PHP