Check the empty table

[JustRun]

Hi,
I just want to know what is the number that will return if the table is empty "has no record"
Is it ' 0 ' ?

[tlhintoq]

"the number"? I'm sure there a many numbers associated with a table. Which one do you mean? Record count would be zero.

TIP: Feel safe to experiment more. What harm can you do? Build two are three small tables. Put no records in one of them. Put 10 records in one of them. Generate 100,000 records for one of them. Use these for your testing. It can be enlightening to see how routines that seem to work fine on 10 records are less than expected at 100,000.

[artov]

There are two cases where zero comes on "empty table":

1. If table's size is zero:

Type table[] = new Type[0];

then Length property (table.Length) of the table is zero.

2. When table is created, its elements contain default value of the Type. If the Type is numeric value, its default value is zero (either integer zero, floating zero or decimal zero). In a way, this kind of table is empty, since there is no application data inserted yet.

[JustRun]

Well here is my Case

public int tableRecords;
 
//public int tableRecords
        //{
        //    get { return _tableRecords; }
        //    set { _tableRecords = value; }
        //}
 
public int CountTableRecords(string _userName, string _projectName)
        {
            try
            {
                cmd = new SqlCommand("SELECT COUNT(ActivationKey) AS ActKey FROM ActivationTable "+
                    " WHERE (UserName = @UserName) AND (ProjectName = @ProjectName)", con);
 
                cmd.Parameters.AddWithValue("UserName", _userName);
                cmd.Parameters.AddWithValue("ProjectName", _projectName);
 
                tableRecords = (Int32)cmd.ExecuteScalar();
            }
            catch (Exception ex)
            {
                msg.err = ex.Message.ToString();
            }
            return tableRecords;
        }
 

Inside the SQL view thi query returns the correct number ( 0=no records , number = records number )
The problem is in my C# code, it always returns 0 ,

Any one can correct my code and tell me why .

Thanks

[r035198x]

Shouldn't

cmd.Parameters.AddWithValue("UserName", _userName);

be

cmd.Parameters.AddWithValue("@UserName", _userName);

instead?

[JustRun]

I don't think so, I always do my queries in that format and it always works, Also I replaced the variables (@UserName, ....) with constant values Still return ZERO :(((((

[r035198x]

@JustRun
That's not what MSDN says. See their examples.
@JustRun
Then either the query does return 0 records or you are getting an exception.

[JustRun]

Well, I fount the problem , the query is correct, the problem in the connection,

As fro the MSDN, they might say so cause this is the recommended format or the standard but it works without the @ sign :)

Really thanks for your reply.

[r035198x]

So you were getting an Exception?

[JustRun]

OH GOD
I thought that I have a problem within the Connection when I tried to test the result directly from a Form, not get it in a business Class then call it in the form

well now I think I should place my code here, it will be long but I'll try to clarify :(

[r035198x]

Better separate all that database access code from your interface code. It makes it easier to debug your code and makes your code reusable.
You should also never connect to databases on the same thread that draws the interface.

[JustRun]

I do that already, but guess what , The same method that counts the table records return the correct number from the interface Form bur return Zero from the business class

I checked the connection , it works with no problem.

I'm Stuck

[r035198x]

Then the method is dependent on something being provided in the form but being provided in the business class.
P.S. Business classes should also not contain any SQL. See the DAO pattern for one way of separating these concerns.

[JustRun]

well, I'm checking my bussiness class again now, and i'll tell you the result
wish me luck :(

[JustRun]

by the way there is no SQL in my bussiness class, but it might there a conflict with (if else) they are much, i'll try to find a way to separate them and organize the code in a better way

[JustRun]

Yesssssssssssssssss,

[JustRun]

IT WORKESSSSSSSSSSS, i just rotate some IF statements with others and it workkssss :D

Thanks for your patient and Quick following
Now I can Take my break ;)

[r035198x]

Yeah I'll go and make myself a cup of Rooibos too.

[JustRun]

hhhhhhhhhhh, yeah ;D