error:specific cast is not valid

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I have run the code in oracle 11g database. sql>select count(*) from treat_info,patient_table where treat_info.pid=patient_table.pid;
The result is count(*)=0
But in C# Windows application the error occurs.

C#

String st = "select count(*) from treat_info,patient_table where treat_info.pid=patient_table.pid";
OracleCommand cmd = new OracleCommand(st);
cmd.Connection = cn;
OracleDataReader rd = cmd.ExecuteReader();
rd.Read();
int c = rd.GetInt32(0);//error in this line specific cast is not valid
MessageBox.Show(c.ToString());

Posted 31-Jul-15 9:16am

Sunil Kumar Das

Updated 31-Jul-15 9:55am

Afzaal Ahmad Zeeshan

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arussell · Accepted Answer · 2015-07-31T11:03:00

Solution 1

check the rd.HasRows. If it is zero then there is no column zero to get the data from so it will be null, not an int and fail, or throw an excpetion

OR column zero doesn't have an int in it, maybe its a float. Try using:
int c = Convert.ToInt32(rd.GetValue(0));

Posted 31-Jul-15 11:03am

arussell

Comments

Sunil Kumar Das 1-Aug-15 0:02am

thanks a lot