how to execute stored procedure in vb.net

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C#

ConnectDatabase()
Cmd = New SqlCommand("stockon2", Con)
Cmd.CommandType = CommandType.StoredProcedure
Cmd.Parameters.AddWithValue("@hd", CInt(14572))
Cmd.Parameters("@hd").Direction = ParameterDirection.Input
Cmd.Parameters.AddWithValue("@dt", CInt(Txtdate.Text))
Cmd.Parameters("@dt").Direction = ParameterDirection.Input
Cmd.Parameters.AddWithValue("@rateonly", CInt(txtip.Text))
Cmd.Parameters("@rateonly").Direction = ParameterDirection.Input
Cmd.Parameters.AddWithValue("@qty", CInt(0))
Cmd.Parameters("@qty").Direction = ParameterDirection.Input
Cmd.Parameters.Add("@val", SqlDbType.Float)
Cmd.Parameters("@val").Direction = ParameterDirection.Output
Cmd.ExecuteReader()
TxtValue.Text = Cmd.Parameters("@val").Value
Con.Close()

i got below attached error

Conversion from type 'dbnull to the string is not valid

Posted 23-Sep-14 2:39am

d.sankaranarayanan

Updated 23-Sep-14 3:00am

Thanks7872

v3

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Comments

[no name] 23-Sep-14 8:49am

Well it's obvious is it not? Your SP is returning null.

Abdul Samad KP 23-Sep-14 9:05am

As Wes Aday said , @val is dbnull. To avoid this error use .ToString()

Cmd.ExecuteNonQuery()
TxtValue.Text = Cmd.Parameters("@val").Value.ToString()

PhilLenoir 23-Sep-14 9:10am

Try running in debug, get the values you are passing and run the query in SQL Management Studio to debug. Best guess, there are no rows being returned, but without seeing your stored proc .....

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Kornfeld Eliyahu Peter · Answer 1 · 2014-09-23T03:31:00

It seems to be obvious - your output parameter (@val) get NULL as value!
If this is an unacceptable result you must check your SP.
If this is an acceptable result change this line:

C#

TxtValue.Text = Cmd.Parameters("@val").Value

to this:

C#

TxtValue.Text = Convert.ToString(Cmd.Parameters("@val").Value)