save result mysql query to variable in VB net - mysql

Question

i have vb such as like this :
Sub inputdata()
Try
koneksi.Open()
***sql2 = "SELECT code_cust from customer where ('nama_cust= " & Me.cbcust.Text & "')"
cmd = New MySqlCommand(sql2, koneksi)
sql3.text=cmd.ExecuteNonQuery()***
sql = "insert into hsmaster(nohs,detailhs,beamasuk,satuanhs,idcust,asal) values ('" & Me.txtnohs.Text & "',"
sql += "'" & Me.rtdetail.Text & " ',"
sql += "'" & Me.txtbm.Text & " ',"
sql += "'" & Me.txtsatuan.Text & " ',"
sql += "'" & sql3 & " ',"
sql += "'" & Me.Cbcountry.Text & " ')"
cmd = New MySqlCommand(sql, koneksi)
cmd.ExecuteNonQuery()
MessageBox.Show("Insert data berhasil dilakukan")
Catch ex As Exception
MessageBox.Show("Insert data Gagal dilakukan")
Finally
koneksi.Close()
End Try
So i want save result of quert sql3 to slq3 , but the result was -1
Please advace ...
sql2 was query to customer table with clause name of customer was loading from combo box customer.
cbcust.text was from combo box loading data from table customer.
thanks for any kind help and sugestion.

Answer 1

ExecuteNonQuery is only for inserts/updates/deletes, queries that you aren't expecting to retrieve data back from. The -1 you are seeing is what databases return when executing a non-query to indicate whether the command was successful. You are correct to use ExecuteNonQuery on your second insert, but for your first select query if you want a value returned, you have to use
sql3.text = cmd.ExecuteScalar
or use a datareader
Dim dr As MySqlDataReader
dr = cmd.ExecuteReader
'check to make sure dr isnot nothing and read it, then
Dim returnValue as string = dr(code_cust)
ExecuteScalar is used for returning a single value and would probably work best in your case, datareader is used when expecting multiple columns and/or rows
You should be using parameters in your query too, but if using quotes like you are then:
***sql2 = "SELECT code_cust from customer where ('nama_cust= " & Me.cbcust.Text & "')"
needs the single quote moved like this:
***sql2 = "SELECT code_cust from customer where (nama_cust= '" & Me.cbcust.Text & "')"
because right now, that's a syntax error