how to handle null table linkq

Question

0.00/5 (No votes)

See more:

its give error for "The null value cannot be assigned to a member with type System.Int32 which is a non-nullable value type."

Here, i have Null table 'Rate'
and i wont to get max no. of rate.id (primary and Auto Increment).
here problem is that if table is Empty then it's show Error
how can i handle it

C#

DataClasses1DataContext dm = new DataClasses1DataContext();
var item = dm.Rates.Max(o => o.Id);
 item = (item) + 1;
    
lblSrno.Containt=item.Tostring();

please help me

Posted 13-Nov-14 18:20pm

mukesh mourya

Updated 14-Nov-14 6:02am

v3

Add a Solution

Comments

BillWoodruff 14-Nov-14 2:23am

It's good programming practice to check for 'null before executing code that will rely on a non-null "something."

4 solutions

Solution 1

You can try the below code.

var item = dm.Rates.Max(o => {if(o!=null && o.id!=null){ return o.id; } });

Posted 13-Nov-14 18:37pm

ashish__shukla

Comments

mukesh mourya 14-Nov-14 12:22pm

It's not work :(

Solution 3

Hi,

You can write like this

C#

try
{
DataClasses1DataContext dm = new DataClasses1DataContext();
var item = dm.Rates.Max(o => o.Id);
if(item==null)return;
 item ++;
lblSrno.Containt=item.Tostring();
}
catch{

}

Check it whether it is working for you..

Posted 13-Nov-14 20:54pm

Jineesh TR

Comments

mukesh mourya 14-Nov-14 12:22pm

It's not work

Jineesh TR 16-Nov-14 22:28pm

then you check null for dm.Rates. I think this is null.

Solution 2

C#

DataClasses1DataContext dm = new DataClasses1DataContext();
var item = dm.Rates.Max(o => o.Id);
 item = (item==null ? 0:item) + 1;
lblSrno.Containt=item.Tostring();

Posted 13-Nov-14 20:06pm

Pravuprasad

Comments

mukesh mourya 14-Nov-14 12:37pm

Not worked

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

/\jmot · Accepted Answer · 2014-11-13T21:08:00

Solution 4

Try this...

C#

int? intIdt = db.Users.Max(u => (int?)u.UserId);

See this link for Explanation.
Null MaxId[^]

Posted 13-Nov-14 21:08pm

/\jmot