How to display the count value on label? - mysql

Question

I have a monitoring in datagridview that has a display of list of vehicles and their types. I want to count the number of each type of the vehicle.
Example : there are 8 Sedans and 5 Motorcycles in the datagridview and I want it to display in the label.
here is my code:
Dim table As New DataTable()
Dim command As New MySqlCommand("select count(ctype) from tblreport where ctype='SUV'", conn)
command.Parameters.Add("count(ctype)", MySqlDbType.VarChar).Value = Label6.Text
Dim adapter As New MySqlDataAdapter(command)
adapter.Fill(table)
DataGridView2.DataSource = table

Answer 1

After you assign the datasource, just add this :
Label1.Text=datagridview1.rows.count
Text is a property of many controls like label,button and others.This property can be used to display an overlay of text over the control. Datagridview has rows ,right ? So, as u said, u want to display the number of rows the datagridview contains.So all you need to do is use Datagridview1.rows.count,i don't think this one needs any explanation at all.
Anyway, let's advance a bit further.
You also said
there are 8 Sedans and 5 Motorcycles in the datagridview and I want it to display in the label.
By default,no application can understand how many records match Sedans and Motorcycles .But as mentioned above, vb is able to calculate the rows of a datagridview(by default/by simple codes).So try to think for once,if the datagridview only had the rows that contained Sedans or Motorcycles in any cell, vb.net could've easily counted it..right ??
So, if u ask me, how do we get only the rows containing Sedans or Motors , then i'ld as u, how does google show only the results u r looking for instead of showing everything it has ?? The answer is simple,google shows exactly what you Search for. When it comes to databases,we call it filtering/sorting/even seaching.So, all you need to do is filter your database.There are couple of ways,which,if i start explaining,would take a lotta time.However,check these :
• http://csharp.net-informations.com/datagridview/csharp-datagridview-filter.htm
• Filtering DataGridView without changing datasource
Now, let's go deeper.If you go through the links above,you'll be able to show only the rows that contain Sedans or so in any of it's cells.What if you want all the rows but only want the label to display the number(row count) of Sedans or so ?
In this case,you can use a Datatable.
Learn more about Datatable here
You can easily use a datatable to count the rows containg only the QUERY u r looking for.For that, u can code as follows :
Dim cmd as new MySqlCommand("Select * from [tablename](columnname)(#value)",con)
cmd.parametres.addwithvalue("#value","Sedan")
Dim table as new DataTable
Dim adap as new MySqlDataAdapter
adap.fill(table)
If table.rows.count <=0 then
Else
LAbel1.text=table.rows.count
Let me explain from dim table.Here i am declaring a datatable.But before that i am filtering the dataset by using cmd.parametres.addwithvalue.Then,i am using a DataAdapter and filling the DataTable with only th e rows containing SEDAN. Now, focus on If table.Rows.Count <=0 Then ...This indicates if there are no rows(which is less than or equals to 0) containing the query.Then i am using the Else statement which means if the datatable contains rows matching the query.In the else statement,i am adding the row count of the Datatable as a string/text in the Label..
I hope this is enough and this explanation will help u in future as well.

Answer 2

Use the same DataTable you have used to fill the DataGridView. Only change your select statement to Select * from tableName. I used the index of 2 but change to whatever it is in your table. The column index starts at zero.
Dim totalSedans As Integer = 0
Dim totalMotorcycles As Integer = 0
Dim totalConvertable As Integer = 0
For Each row As DataRow In table.Rows
Select Case row(2).ToString
Case "Sedan"
totalSedans += 1
Case "Motorcycle"
totalMotorcycles += 1
Case "Convertable"
totalConvertable += 1
Case Else
Debug.Print("Something doesn't match categories")
End Select
Next
lblConvertable.Text = totalConvertable.ToString
lblMotorcycles.Text = totalMotorcycles.ToString
lblSedan.Text = totalSedans.ToString