Getting an ORA-01426: Numeric Overflow in .NET 4.0, C#, using the Oracle DataAccess .dll

I am trying to write a very simple webpage using Visual Studio 2010, .Net 4, C#. I am using the Oracle DataAccess .DLL and have made a connection to the database just fine. When I run this code, I get the exception 'ORA-01426: Numeric Overflow." I am not doing any calculations, and I put the whole thing into a string before I submit the query开发者_运维百科. Below is my code sample:

string sql = "SELECT * from users.training WHERE per_id_no = " + strIdNo;
        OracleCommand cmd = new OracleCommand(sql, conn);
        cmd.CommandType = System.Data.CommandType.Text;

        try
        {
            Label1.Visible = false;
            //Read data from the database
            OracleDataReader dr = cmd.ExecuteReader(); // C#
            dr.Read();

This is not an answer, but your code is vulnerable to SQL injection. Never include parameters directly into the SQL statement. Use named arguments instead:

    string sql = "SELECT * from users.training WHERE per_id_no = @id";
    using (var cmd = conn.CreateCommand()) 
    {
        cmd.CommandText = sql;

        //syntax differs between different providers
        cmd.Parameters.Add("id", strIdNo); 

        try
        {
            Label1.Visible = false;
            OracleDataReader dr = cmd.ExecuteReader();
            dr.Read();
        }
     }

If per_id_no is a varchar2 data type then you probably need to put the value in single quotes.
string sql = "SELECT * from users.training WHERE per_id_no = '" + strIdNo + "'";

Of course, I entirely agree with @jgauffin, in which case I think the query should look like this
string sql = "SELECT * from users.training WHERE per_id_no = '@id'";
But I am pretty sure in Oracle the paramter should be :id and not @id which I believe is SQL Server syntax.

Anyway, HTH
Harv

strIdNo may be too large for the type that would contain it. Check to be sure it doesn't need to be quoted (to convert it into a string). Also check the type of the per_id_no column to make sure it is the type you expect (and that strIdNo can fit in it).