How to quick update MySQL table through a loop using VB.net - vb.net

Question

My code for updating mysql table having more than 2000 rows through a loop using VB.net is working fine but too slow. Is there any way to update it faster ? Anybody please help. Thanks. My code is given below.
Dim mysqlconn = New MySqlConnection
mysqlconn.ConnectionString = "server=localhost;user id=root;password=1234;database=Share"
mysqlconn.Open()
Dim adapter As New MySqlDataAdapter("SELECT * FROM name_list;", mysqlconn)
Dim datatable As New DataTable()
adapter.Fill(datatable)
Dim cmd As New MySqlCommand
cmd.Connection = mysqlconn
Dim sql As String
Dim i as integer = 0
While i <= datatable.Rows.Count - 1
Dim sy As String = datatable.Rows(i).Item(3).ToString.Trim
sql = "UPDATE Name_list Set Numerology = '" & "N-" & variable1 & " S- " & variable2 & "',FSTLetter = '" & variable3 & "',Timing = '" & vriable4 & "',P_Numerology = '" & variable5 & "' WHERE Symbol = '" & sy & "'"
sy = ""
cmd.CommandText = sql
cmd.ExecuteNonQuery()
i = i + 1
End While
adapter.Fill(datatable)
DataGridView1.DataSource = datatable
DataGridView1.Refresh()

Answer 1

Don't name variables the same as class names (DataTable, datatable) vb.net is case insensitive so it confuses intellisense.
Database connections and commands need to closed and disposed.
Using blocks do this for you even if there is an error.
You can set the connection string by passing it directly to the constructor of the connection. Likewise, you can set the command text and the connection by passing to the constructor of the command.
Don't open the connection until right before it is used. In this case we don't need a DataAdapter but if you are using one it is not necessary to open the connection at all. The .Fill method of the DataAdapter will open and close the connection. However if the DataAdapter finds an open connection it will leave it open.
To avoid confusion, I created 2 data tables. I used a single connection but I opened and closed it each time it is used. It is not disposed until the last End Using.
The first command retrieves only the sy column. Replace Column4_Name with the actual column name. We don't want to pull down data we don't need so no Select *.
Always use parameters to avoid sql injection which can damage your database. You need to check your database for the types of the fields. I had to guess. Each parameters value is set except sy which changes on each iteration.
No need to close the connection after the last Select command since the final End Using will close and dispose.
After the connection is closed we update the user interface.
Private Sub OPCode(variable1 As String, variable2 As String, variable3 As String, variable4 As String, variable5 As String)
Dim dtBeforeUpdate As New DataTable()
Dim dtAfterUpdate As New DataTable()
Using mysqlconn = New MySqlConnection("server=localhost;user id=root;password=1234;database=Share")
Using cmd As New MySqlCommand("SELECT Column4_Name FROM name_list;", mysqlconn)
mysqlconn.Open()
dtBeforeUpdate.Load(cmd.ExecuteReader)
mysqlconn.Close()
End Using
Using cmd As New MySqlCommand($"UPDATE Name_list Set Numerology = #Numerologh, FSTLetter = #FST, Timing = #Timing, P_Numerology = #P_Numerology WHERE Symbol = #sy ", mysqlconn)
cmd.Parameters.Add("#Numerology", MySqlDbType.String).Value = $"N-{variable1} S- {variable2}"
cmd.Parameters.Add("#FST", MySqlDbType.String).Value = variable3
cmd.Parameters.Add("#Timing", MySqlDbType.String).Value = variable4
cmd.Parameters.Add("#P_Numerology", MySqlDbType.String).Value = variable5
cmd.Parameters.Add("#sy", MySqlDbType.String)
mysqlconn.Open()
For Each row As DataRow In dtBeforeUpdate.Rows
cmd.Parameters("#sy").Value = row(0).ToString.Trim
cmd.ExecuteNonQuery()
Next
mysqlconn.Close()
End Using
Using cmd As New MySqlCommand("Select * From Name_list;", mysqlconn)
mysqlconn.Open()
dtAfterUpdate.Load(cmd.ExecuteReader)
End Using
End Using
DataGridView1.DataSource = dtAfterUpdate
End Sub
Actually, I don't get it. It seems like you are updated the entire table with the same data. Do you expect the variable1, variable2 etc. to change somehow?

Answer 2

Don't know where your variable1, variable2, etc come from, but those look to be static, so your loop is somewhat pointless it would seem. You're updating every row in the loop to the exact same values (unless there's other code you're not showing), so just update the table without the loop:
Using con As New MySQLConnection
con.ConnectionString = "server=localhost;user id=root;password=1234;database=Share"
con.Open
Using cmd As New MySQLCommand
cmd.Connection = con
cmd.CommandText = "UPDATE Name_list Set Numerology = '" & "N-" & variable1 & " S- " & variable2 & "',FSTLetter = '" & variable3 & "',Timing = '" & vriable4 & "',P_Numerology = '" & variable5 & "'"
cmd.ExecuteNonQuery
End Using
End Using