mysql - Strange issue when retrieving data from my database -


when reading data table, 1 of numerical values returns -1, rather value given user.

private sub form1_load(sender object, e eventargs) handles mybase.load     try         dim conn new mysqlconnection("server=localhost;user=root;database=new_project;port=3306;password=********;")         conn.open()         dim command new mysqlcommand("select * students;", conn)         dim dataset new dataset()         dim dataadapter new mysqldataadapter()         dataadapter.selectcommand = command         dataadapter.fill(dataset, "students")         dim datatable datatable = dataset.tables("students")         x integer = 0 datatable.rows.count - 1             dim newstudent new student             newstudent.intidnum = datatable.rows(x).item("idnumber")             newstudent.strfirstname = datatable.rows(x).item("firstname")             newstudent.strlastname = datatable.rows(x).item("lastname")             newstudent.chrgender = datatable.rows(x).item("gender")             newstudent.datedob = datatable.rows(x).item("dateofbirth")             newstudent.intage = cint(today.year - newstudent.datedob.year)             newstudent.intyeargroup = datatable.rows(x).item("yeargroup")             newstudent.intskilllevel = datatable.rows(x).item("skilllevel")             studentlist.add(newstudent)             lststudents.items.add(newstudent.nameconcat(newstudent.strfirstname, newstudent.strlastname))         next         conn.close()     catch ex exception         msgbox("error: " & ex.tostring())     end try end sub

when reading value "skilllevel", should read between 1 , 4, instead reads -1. hasn't occurred data added directly database through mysql, when using method in program, seems issue appears.

dim newstudent new student         newstudent.strfirstname = txtforename.text         newstudent.strlastname = txtsurname.text         newstudent.datedob = dtpstudentdob.value         if rdbmale.checked = true             newstudent.chrgender = "m"         else             newstudent.chrgender = "f"         end if         newstudent.intage = newstudent.calcage(dtpstudentdob.value)         newstudent.intskilllevel = cmbskilllevel.selecteditem         newstudent.intyeargroup = cmbyeargroup.selecteditem         newstudent.intidnum = cint(txtstudentid.text)         dim conn new mysqlconnection("server=localhost;user=root;database=new_project;port=3306;password=********;")         try             conn.open()             dim command mysqlcommand = new mysqlcommand             command.connection = conn             command.commandtext = "insert students values(@idnumber, @firstname, @lastname, @gender, @dateofbirth, @yeargroup, @skilllevel);"             command.prepare()             command.parameters.addwithvalue("@idnumber", newstudent.intidnum)             command.parameters.addwithvalue("@firstname", newstudent.strfirstname)             command.parameters.addwithvalue("@lastname", newstudent.strlastname)             command.parameters.addwithvalue("@gender", newstudent.chrgender)             command.parameters.addwithvalue("@dateofbirth", newstudent.datedob)             command.parameters.addwithvalue("@yeargroup", newstudent.intyeargroup)             command.parameters.addwithvalue("@skilllevel", newstudent.intskilllevel)             command.executenonquery()         catch ex exception             msgbox("error: " & ex.tostring())                     conn.close()         end try

this section of code student added system. causing error appear?

for reference, main form add in data uses enumeration:

private enum skilllevels integer     1 = 1     2 = 2     3 = 3     4 = 4 end enum

and link dropdown: cmbskilllevel.datasource = system.enum.getvalues(gettype(skilllevels))

the obvious possibility no selection made in skill-level dropdown , why getting -1, can check if selection has been made in dropdown ensuring not -1

for example skills drop down may this

<select id="skilllevel">   <option value="0" selected="selected">please select</option>   <option value="1">low</option>   <option value="2">medium</option>   <option value="3">high</option>   <option value="4">very-high</option> </select>

if no selection made default value returned 0 (0) , can check valid values looking returned values > 0

as far can remember if omit selected="selected" returned value -1


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