how to retrieve mysql data in vb.net? - mysql

Question

im trying to retrieve mysql data with specific column and show to textbox in vb.net. what should i do in retrieving it?
Dim connect As New MySqlConnection("server=localhost; user id=root; password= ; database=ticketing_system;")
connect.Open()
Dim sqladapter As New MySqlDataAdapter
Dim sqlcmd As New MySqlCommand
Dim dr As MySqlDataReader
Dim dt As New DataTable
sqlcmd = New MySqlCommand("SELECT * complaint WHERE tran_no='" & lbltranno.Text & "'")
**THEN? WHAT SHOULD I DO TO DISPLAY DATA? PLEASE HELP**
connect.Close()

Answer 1

You are simply missing the Execution method. It depends on what kind of result you want. If you only want the first result from the query (first row and first column) then use sqlcmd.ExecuteScalar().
If you want all the results you'll have to load that into a MySqlDataReader using the method sqlcmd.ExecuteReader()
Using ExecuteReader() :
Dim connect As New MySqlConnection("server=localhost; user id=root; password= ; database=ticketing_system;")
connect.Open()
Dim sqladapter As New MySqlDataAdapter
Dim sqlcmd As New MySqlCommand
Dim dr As MySqlDataReader
Dim dt As New DataTable
sqlcmd = New MySqlCommand("SELECT * complaint WHERE tran_no='" & lbltranno.Text & "'")
dr = sqlcmd.ExecuteReader()
dt.Load(dr)
'Useable datatable in dt variable...
connect.Close()
Using ExecuteScalar() :
Dim connect As New MySqlConnection("server=localhost; user id=root; password= ; database=ticketing_system;")
connect.Open()
Dim sqladapter As New MySqlDataAdapter
Dim sqlcmd As New MySqlCommand
Dim dr As String
Dim dt As New DataTable
sqlcmd = New MySqlCommand("SELECT [COLUMN NAME] complaint WHERE tran_no='" & lbltranno.Text & "'")
dr = sqlcmd.ExecuteScalar()
'dr now contains the value of [COLUMN NAME] for the first returned row.
connect.Close()

Answer 2

You can try this:
Dim connString As String = "server=localhost; user id=root; password=[REPLACE WITH PASSWORD] ; database=ticketing_system;"
Dim sqlQuery As String = "SELECT * from complaint WHERE tran_no='" & lbltranno.Text & "'";
Using sqlConn As New MySqlConnection(connString)
Using sqlComm As New MySqlCommand()
With sqlComm
.Commandtext = sqlQuery
End With
Try
sqlConn.Open()
Dim sqlReader As MySqlDataReader = sqlComm.ExecuteReader()
While sqlReader.Read()
Label1.Text = sqlReader("Name").ToString()
Label2.Text = sqlReader("Points").ToString()
End While
Catch ex As MySQLException
' add your exception here '
End Try
End Using
End Using

Answer 3

Imports System.Data.SqlClient
Public Class Form1
Dim c As New SqlConnection("Data Source=SONY;Initial Catalog=msdb;Integrated Security=True")
Dim cmd As New SqlCommand
Dim da As New SqlDataAdapter
Dim dr As SqlDataReader
Dim ds, ds1 As New DataSet
Private Sub btnsub_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnsub.Click
Try
ds.Clear()
c.Open()
cmd = New SqlCommand("select Sub_Name from Subject_Detail WHERE Course='" + txtcourse.Text + "'", c)
da = New SqlDataAdapter(cmd)
da.Fill(ds, "Subject_Detail")
Label1.Text = ds.Tables(0).Rows(0).Item(0)
Label2.Text = ds.Tables(0).Rows(1).Item(0)
Label3.Text = ds.Tables(0).Rows(2).Item(0)
Label4.Text = ds.Tables(0).Rows(3).Item(0)
Label5.Text = ds.Tables(0).Rows(4).Item(0)
Label6.Text = ds.Tables(0).Rows(5).Item(0)
Catch ex As Exception
MsgBox(ex.Message)
Finally
c.Close()
End Try
End Sub
End Class
'This code display all subject name from the table into labels.This might be helped.

Answer 4

Try this one, i always use this code, that's why i'm pretty sure that this will work...
Imports MySql.Data
Imports MySql.Data.MySqlClient
Dim connect As New MySqlConnection("server=localhost;uid=root;database=ticketing_system;pwd=;")
connect.Open()
Dim sqlcmd As New MySqlCommand("SELECT * complaint WHERE tran_no='" & lbltranno.Text & "'")
Dim sqladapter As New MySqlDataAdapter(sqlcmd)
Dim dt As New DataTable
sqladapter.Fill(dt)
Datagridview1.Datasource = dt
connect.Close()

Answer 5

Imports MySql.Data
Imports MySql.Data.MySqlClient
Dim dbConnection As New MySqlConnection("server=localhost;uid=youruser;database=yourdb;pwd=password")
try
dbConnection.open
catch ex as exception
debug.print(ex.message)
end try
using Adapter as new mysqldataadapter("select * from yourtable where yourcolumn = 'yourvalue'", dbConnection)
using Table as new datatable
Adapter.fill(Table)
Datagridview.datasource = table
end using
end using
dbConnection.close

Answer 6

Imports MySql.Data.MySqlClient
''--- Data Reader Example
private _cn as New MySqlConnection( _
"data source=server; database=databaseName; user id=username; password=password")
private cmd as new MySqlCommand
private dr as MySqlDataReader
With cmd
.Command = "select Name, Address from Clients"
.CommandType = CommandType.Text
.Connection = cn
End With
cn.Open()
dr = cmd.ExecuteReader
While dr.Read
'' use dr(0) for get Name, and dr(1) to get Address for this example
Console.WriteLine(dr(0) & " - " & dr(1))
Console.WriteLine(dr("Name").ToString() & " - " & dr("Address").ToString())
End While
dr.Close
cn.Close

Answer 7

Dim MysqlConn As MySqlConnection
Dim connectionString As String = "Server=-host-ip-;Database=Mysqldb;Uid=user;Pwd=password"
MysqlConn = New MySqlConnection(connectionString)
Try
Dim Mysqlcmd As New MySqlCommand("SELECT * FROM Mysqldb.table WHERE col='" & Label6.Text & "'", MysqlConn)
Dim dt As New DataTable
Dim Mysqladapter As New MySqlDataAdapter()
MysqlConn.Open()
Mysqladapter.SelectCommand = Mysqlcmd
Mysqladapter.Fill(dt)
DataGridView1.DataSource = dt
MessageBox.Show("Connection to Database has been opened.")
MysqlConn.Close()
Catch myerror As MySqlException
MessageBox.Show("Cannot connect to database: " & myerror.Message)
Finally
MysqlConn.Dispose()
End Try
The key is to add the connection at the end of the mysql query as in line 6

Answer 8

I used a variation of the code given in this thread with Visual Basic 2015. I found I needed a 2nd argument in the MySqlCommand statement, namely the MySqlConnection variable ("connect" in some of the examples). See thread: Connection must be valid and open VB.Net
Thanks for the help.