If I only add one query such as hostnameQuery the code works fine, as you can see I have tried to add multiple.
I've tried using + and & on the MySqlCommand but I get a syntax error returned.
Dim hostnameQuery As String = "SELECT `HOSTNAME` FROM `m1` WHERE 1"
Dim osQuery As String = "SELECT `OS` FROM `m1` WHERE 1"
Dim SQLConnection As New MySqlConnection(My.Settings.connStr)
Dim cmd As New MySqlCommand(hostnameQuery & osQuery, SQLConnection)
Try
SQLConnection.Open()
cmd.ExecuteNonQuery()
Dim reader As MySqlDataReader
reader = cmd.ExecuteReader
While reader.Read
main.Label64.Text = (reader.GetString(0))
main.Label65.Text = (reader.GetString(0))
End While
Catch ex As Exception
MsgBox(ex.Message.ToString)
Finally
SQLConnection.Close()
End Try
try:
Dim hostnameQuery As String = "SELECT `HOSTNAME` FROM `m1` WHERE 1 UNION ALL (SELECT `OS` FROM `m1` WHERE 1)";
or you why not (since you quering 1 table):
Dim hostnameQuery As String = "SELECT `HOSTNAME`,`OS` FROM `m1` WHERE 1 ";
.....
While reader.Read
main.Label64.Text = (reader.GetString(0))
main.Label65.Text = (reader.GetString(1))
Related
There are 10 rows in primary_student_table.
When I execute the following code, the result was -1.
Dim count As Int16
con.Open()
query = "SELECT COUNT(roll) AS rollcount FROM primary_student_table WHERE admityear = 2011 AND batch = 1 "
cmd = New SqlCommand(query, con)
count = cmd.ExecuteNonQuery
MsgBox(count)
con.Close()
What's the problem in the above code?
You should be using ExecuteScalar() rather than ExecuteNonQuery() because you are fetching a value.
count = Convert.ToInt16(cmd.ExecuteScalar())
MsgBox(count.ToString())
SqlCommand.ExecuteScalar Method
For proper coding
use using statement for proper object disposal
use try-catch block to properly handle exceptions
Example Code:
Dim connStr As String = "connection string here"
Dim query As String = "SELECT COUNT(roll) AS rollcount FROM primary_student_table WHERE admityear = 2011 AND batch = 1"
Using conn As New SqlConnection(connStr)
Using cmd As New SqlCommand()
With cmd
.Connection = conn
.CommandText = query
.CommandType = CommandType.Text
End With
Try
conn.Open()
Dim count As Int16 = Convert.ToInt16(cmd.ExecuteScalar())
MsgBox(count.ToString())
Catch(ex As SqlException)
' put your exception here '
End Try
End Using
End Using
The solution is to replace
count = cmd.ExecuteNonQuery
with
count = cmd.ExecuteScalar
Like Robert Beaubien said in his comments
MysqlConn = New MySqlConnection
MysqlConn.ConnectionString = "server=localhost;userid=root;password=1234;database=dblms"
Dim READER As MySqlDataReader
Try
MysqlConn.Open()
Dim Query As String
Query = "Select * from dblms.accounts"
COMMAND = New MySqlCommand(Query, MysqlConn)
READER = COMMAND.ExecuteReader
Dim count As Integer
count = 0
While READER.Read
count = count + 1
End While
MysqlConn.Close()
Catch ex As MySqlException
MessageBox.Show(ex.Message)
Finally
MysqlConn.Dispose()
End Try
the value in count will be the number of rows in a table :) hope this helped
I'm working on my project which displays a list of employee. here, the information and picture of the employee will be shown. my project can now show the list of employees in the listbox and when I double click on an employee, his/her profile will be shown on a textbox. my problem is that i can't make their pictures to show in the picturebox. I already stored their picture on a table in my database along with their id, name, and profile. It only shows the picture of the first employee on the table. can anybody help me?
here's what I already done:
I populated the listbox:
Call Connect()
With Me
STRSQL = "Select employee_name from Employees"
Try
myCmd.Connection = myConn
myCmd.CommandText = STRSQL
reader = myCmd.ExecuteReader
If (reader.Read()) Then
reader.Close()
adptr.SelectCommand = myCmd
adptr.Fill(dt)
lstEmployee.DisplayMember = "employee_name"
lstEmployee.ValueMember = "employee_id"
If dt.Rows.Count > 0 Then
For i As Integer = 0 To dt.Rows.Count - 1
lstEmployee.Items.Add(dt.Rows(i)("employee_name"))
Next
End If
End If
Catch ex As Exception
MsgBox(ex.Message)
End Try
End With
here's how I show the info on textbox
Dim FileSize As UInt32
Dim mStream As New System.IO.MemoryStream()
Dim arrImage() As Byte = mStream.GetBuffer()
FileSize = mStream.Length
Dim cmd As New MySqlCommandBuilder
Call Connect()
With Me
STRSQL = "select employee_name, profile from Employees where employee_id = " & lstEmployee.SelectedIndex
Try
myCmd.Connection = myConn
myCmd.CommandText = STRSQL
reader = myCmd.ExecuteReader
If (reader.Read()) Then
txtName.Text = reader("employee_name")
txtProfile.Text = reader("profile")
End If
Catch ex As Exception
MsgBox(ex.Message)
Finally
myConn.Close()
End Try
adptr.SelectCommand = myCmd
dt = New DataTable
adptr = New MySqlDataAdapter("select picture from Employees", myConn)
cmd = New MySqlCommandBuilder
adptr.Fill(dt)
Dim lb() As Byte = dt.Rows(0).Item("picture")
Dim lstr As New System.IO.MemoryStream(lb)
pix.Image = Image.FromStream(lstr)
pix.SizeMode = PictureBoxSizeMode.StretchImage
lstr.Close()
You miss the where clause is must be like to search a one employee to view there image.
adptr = _
New MySqlDataAdapter("select picture from Employees " + _
"where employee_id = " & lstEmployee.SelectedIndex, myConn)
cmd = New MySqlCommandBuilder
adptr.Fill(dt)
Dim lb() As Byte = dt.Rows(0).Item("picture")
Dim lstr As New System.IO.MemoryStream(lb)
pix.Image = Image.FromStream(lstr)
pix.SizeMode = PictureBoxSizeMode.StretchImage
lstr.Close()
P.S.: You must study the LINQ (Language-Integrated Query) for better approach.
Can anyone help me on this? What I wanted to happen is that if the value exist in Table 1 (employee), it will then check Table 2 (mobilelist) if it also exist there. Here's the code:
Private Sub TextBox_IDNumber_LostFocus(sender As Object, e As EventArgs) Handles TextBox_IDNumber.LostFocus
Mysqlconn = New MySqlConnection
Mysqlconn.ConnectionString = "server=localhost;userid=root;password=12345;database=my_db"
Dim READER As MySqlDataReader
Dim READER2 As MySqlDataReader
Dim _isFound As Boolean = False
Dim _isExist As Boolean = False
Try
Mysqlconn.Open()
Dim empmr As String
Dim empml As String
Dim fn1 As String
Dim fn2 As String
Dim ln1 As String
Dim ln2 As String
empmr = "Select * from my_db.employee where IDNumber ='" & TextBox_IDNumber.Text & "'"
empml = "Select * from my_db.mobilelist where IDNumber = '" & TextBox_IDNumber.Text & "' AND DateAssigned is not Null AND DateReturned is Null"
Command = New MySqlCommand(empmr, Mysqlconn)
READER = Command.ExecuteReader
While READER.Read()
_isFound = True
fn1 = READER.GetString("FirstName")
ln1 = READER.GetString("LastName")
End While
If _isFound Then
TextBox_FirstName.Text = fn1
TextBox_LastName.Text = ln1
ElseIf Not _isExist Then
MessageBox.Show("Record Not Found in Master Data")
TextBox_IDNumber.Clear()
TextBox_FirstName.Clear()
TextBox_LastName.Clear()
TextBox_IDNumber.Focus()
End If
Catch ex As MySqlException
MessageBox.Show("Error!")
Finally
Mysqlconn.Dispose()
End Try
End Sub
Assuming you have the appropriate Primary Key and Foreign Key relationship between the tables Employee and MobileList you use this query to find records on the MobileList table for an employee:
Dim myQuery as string
myQuery = "SELECT FirstName, LastName, MobileNumber
FROM Employee
JOIN MobileList
ON Employee.IDNumber=MobileList.IDNumber
WHERE Employee.IDNumber=#ID"
Note: You should rename the IDNumber column on the MobileList to avoid confusion.
You should also improve your access to the database with the Using statement and take advantage of Parameters to prevent SQL injection:
Using myConn As New SqlConnection("Your connection string")
myConn.Open()
Using myCmd As New SqlCommand(myQuery, myConn)
myCmd.Parameters.AddWithValue("#ID", "Your ID value")
Using myReader As SqlDataReader = myCmd.ExecuteReader()
If myReader.HasRows Then
'There are mobile numbers issued to that ID'
Do While myReader.Read()
'Iterate through all existing records'
Loop
Else
'There are no mobile numbers issued to that ID'
End If
End Using
End Using
End Using
Keep in mind that this gives you the mobile numbers for a particular employee, it doesn't tell you if a particular employee exists.
I have this problem:
MySQL server version for the right syntax to use near 'where no ='count'' at line 1
This is my code:
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
MysqlConn = New MySqlConnection
MysqlConn.ConnectionString = "server=localhost;userid=root;password=;database=penjara"
Dim Reader As MySqlDataReader
MysqlConn.Open()
Dim query As String
Dim spath As String
Dim count As Integer = 0
Dim mysound As Media.SoundPlayer
Dim cmd As MySqlCommand
Dim rdr As MySqlDataReader
query = "Select * from penjara.info"
Command = New MySqlCommand(query, MysqlConn)
Reader = Command.ExecuteReader
While Reader.Read
Reader.Close()
count = count + 1
query = "Select penjara.info where no ='count'"
cmd = New MySqlCommand(query, MysqlConn)
rdr = cmd.ExecuteReader
End While
End Sub
How can I solve this error?
Try this:
query = "Select * from penjara.info where no = '" & count & "'"
This will pass in the value of variable count. However, note that this is an unsafe approach since concatenating to form queries makes your app vulnerable to SQL Injection. Instead you should use parameterised queries.
Dim connStr As String = "server=localhost;userid=root;password=;database=penjara"
Using MySqlConn As New MySqlConnection(connStr)
Using cmd As New MySqlCommand()
With cmd
.Connection = MySqlConn
.CommandText = "Select * from penjara.info where no = #count"
.CommandType = CommandType.Text
.Parameters.AddWithValue("#count", count)
End With
Try
MySql.Open()
rdr = cmd.ExecuteReader
Catch ex As Exception
<handle exception>
End Try
End Using
End Using
I have queried my MySql database and data is stored in a dataset named Search Events(I have checked this and it works)
However when i try to pass this data into a datagridview and then ultimately my array it doesn't seem to work :( The problem seems to be that no data is being passed from Search Events into Table
Any ideas??
Dim Table As New DataGridView
Table.DataSource = SearchEvents.Tables("Event ID")
Dim EventID(Table.Rows.Count - 1) As String
For i = 0 To 12
EventID(i) = Table.Rows(0).Cells(i).Value
Next
'Try the following function
Public Sub getuserlist()
Dim con As New MySqlConnection(ConnectionString)
Try
If con.State <> ConnectionState.Open Then
con.Open()
End If
Dim selecttaxinv = "SELECT * FROM user_tb WHERE user_status = 'Active' ORDER BY date_registered DESC"
Dim myCommand As New MySqlCommand(selecttaxinv, con)
Dim dr As MySqlDataReader
dr = myCommand.ExecuteReader()
yourdatagridview.Rows.Clear()
Dim b = 1
While dr.Read()
Dim fullname As String = dr("fname") & " " & dr("mname") & " " & dr("lname")
Dim row As String() = New String() {dr("user_id"), b, fullname, dr("fname"), dr("date_registered")}
yourdatagridview.Rows.Add(row) 'print list
b += 1
End While
dr.Close()
If con.State = ConnectionState.Open Then
con.Close()
End If
Catch ex As Exception
MessageBox.Show(ex.Message, "Information", MessageBoxButtons.OK, MessageBoxIcon.Information)
End Try
End Sub