Object cannot be cast from DBNull to other types

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Object cannot be cast from DBNull to other types

Author

Topic

shemayb
Posting Yak Master

159 Posts

Posted - 2008-03-26 : 04:38:48

I really can't fix this exception..Could please someone help me with this?What would be the first thing that i will examine in my code?

Funnyfrog

SwePeso
Patron Saint of Lost Yaks

30421 Posts

Posted - 2008-03-26 : 07:08:39

Change line 13 to "RETURN".

E 12°55'05.25"
N 56°04'39.16"

jsmith8858
Dr. Cross Join

7423 Posts

Posted - 2008-03-26 : 07:13:52

I disagree, try removing lines 10 through 17 and replacing them with:

if a>b then x=d

That should do it.

- Jeff
http://weblogs.sqlteam.com/JeffS

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2008-03-26 : 07:14:02

what you have to do is:
rdr["yourCol"] has a value of DbNull
you have to perform the check for this and either cast it to null or a value if it's not a reference type.

show us your code for better help

_______________________________________________
Causing trouble since 1980
blog: http://weblogs.sqlteam.com/mladenp
SSMS Add-in that does a few things: www.ssmstoolspack.com

shemayb
Posting Yak Master

159 Posts

Posted - 2008-03-26 : 21:42:46

here's my code:

protected void btnAddTAC_Click(object sender, System.EventArgs e)
{

PatientDetail patientDetail = PatientCache;

DataTable dt = patientDetail.TACs;

int maxid = 1;

if (dt.Rows.Count > 0)
maxid = Convert.ToInt32(dt.Compute("MAX(tac_keyid)", "")) + 1;(my error is this part)

DataRow dr = dt.NewRow();
dr["keyid"] = maxid;
dr["fromdate"] = DateTime.Parse(calFromDate.Text);
dr["thrudate"] = DateTime.Parse(calThruDate.Text);
dr["tac"] = tbTAC.Text.Trim();
dr["create_date"] = DateTime.Now;

dt.Rows.Add(dr);

BindTCs();

Funnyfrog

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2008-03-27 : 06:25:26

yes and since your tac_keyid value is null the whole dt.Compute("MAX(tac_keyid)", "") is null and convert fails.

_______________________________________________
Causing trouble since 1980
blog: http://weblogs.sqlteam.com/mladenp
SSMS Add-in that does a few things: www.ssmstoolspack.com

shemayb
Posting Yak Master

159 Posts

Posted - 2008-04-02 : 12:48:18

What makes it null?

Funnyfrog

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2008-04-02 : 13:08:25

that's its value in the database.

_______________________________________________
Causing trouble since 1980
blog: http://weblogs.sqlteam.com/mladenp
SSMS Add-in that does a few things: www.ssmstoolspack.com

ayamas
Aged Yak Warrior

552 Posts

Posted - 2008-04-04 : 07:54:48

From your stored procedure avoid the Null values from coming to you datatable.
Something like ...where tac_keyid is not null

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