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I am using four timers and I think I need to use each one on a different thread.
I am somewhat new to VB. I have learned a lot in the last 10 months.
I just need someone to show me how to use threads w/timers. PLZ post some small
coding on how todo this.
Thanks in advance for everybodies help.
rspercy
If "You wash your feet and find a pair of socks " Then
"You ARE a Redneck"
End If
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There are two types of timers available in .NET framework
1 - System.Threading.Timer[^]
2 - System.Windows.Forms.Timer[^]
The first timer runs a methods on a thread pool thread and the second one runs the method on the same thread. Second one is used with windows forms.
rspercy60 wrote: I am using four timers and I think I need to use each one on a different thread.
What type of timer are you using? You need to tell use, why you think each one should be executed on a different thread?
rspercy60 wrote: I just need someone to show me how to use threads w/timers. PLZ post some small
Looks at the MSDN documentation which I linked to see how timer is used. For threading, this[^] would be the excellent material available on-line.
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I am using System.Windows.Forms.Timers. I have three controls, each control has to be activated
at the same time. Here is one timers code.
Private Sub TMPTimer_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TMPTimer.Tick
If oldTemp < newTemp Then
oldTemp += 1
DirectCast((Me.BaseUI1.Frame(0)), CircularFrame).ScaleCollection(0).Pointer(0).Value = oldTemp
If oldTemp = newTemp Then
oldTemp = newTemp
DirectCast(Me.BaseUI1.Frame(0).FrameCollection(0), NumericalFrame).Indicator.DisplayValue = oldTemp.ToString() & "°"
TMPTimer.Enabled = False
End If
End If
If oldTemp > newTemp Then
oldTemp -= 1
DirectCast((Me.BaseUI1.Frame(0)), CircularFrame).ScaleCollection(0).Pointer(0).Value = oldTemp
If oldTemp = newTemp Then
oldTemp = newTemp
DirectCast(Me.BaseUI1.Frame(0).FrameCollection(0), NumericalFrame).Indicator.DisplayValue = oldTemp.ToString() & "°"
TMPTimer.Enabled = False
End If
End If
End Sub
This code is for a temperature guage, I have two other guages for wind direction and wind speed and all have to be activated at the same time. This is why I think I need threeds
rspercy
If "You wash your feet and find a pair of socks " Then
"You ARE a Redneck"
End If
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I take it you need them all activated because you want the three incoming values to be taken at exact the same time?
If you make all four measurements in a single timer's tick event, they will be received within less than a millisecond of each other (depending on your computer ofcourse).
If you create four threads, they will each be activated from the main thread, within less than a millisecond from each other (depending on your computer ofcourse).
See where I am going with this?
My advice is free, and you may get what you paid for.
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THNX a lot. Worked great. I added all into 1 timer, fantastic.
rspercy
If "You wash your feet and find a pair of socks " Then
"You ARE a Redneck"
End If
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By the way, the code you posted contains some flaws that will cause part of the code to never execute:
Private Sub TMPTimer_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TMPTimer.Tick
If oldTemp < newTemp Then
oldTemp += 1
DirectCast((Me.BaseUI1.Frame(0)), CircularFrame).ScaleCollection(0).Pointer(0).Value = oldTemp
'The following code will never be executed
'because you already established that oldTemp is smaller than newTemp:
If oldTemp = newTemp Then
oldTemp = newTemp
DirectCast(Me.BaseUI1.Frame(0).FrameCollection(0), NumericalFrame).Indicator.DisplayValue = oldTemp.ToString() & "°"
TMPTimer.Enabled = False
End If
End If
If oldTemp > newTemp Then
oldTemp -= 1
DirectCast((Me.BaseUI1.Frame(0)), CircularFrame).ScaleCollection(0).Pointer(0).Value = oldTemp
'The following code will never be executed
'because you already established that oldTemp is larger than newTemp:
If oldTemp = newTemp Then
oldTemp = newTemp
DirectCast(Me.BaseUI1.Frame(0).FrameCollection(0), NumericalFrame).Indicator.DisplayValue = oldTemp.ToString() & "°"
TMPTimer.Enabled = False
End If
End If
End Sub
Move the bit that is the same in both:
Private Sub TMPTimer_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TMPTimer.Tick
'Is it smaller?
If oldTemp < newTemp Then
oldTemp += 1
DirectCast((Me.BaseUI1.Frame(0)), CircularFrame).ScaleCollection(0).Pointer(0).Value = oldTemp
End If
'Is it larger?
If oldTemp > newTemp Then
oldTemp -= 1
DirectCast((Me.BaseUI1.Frame(0)), CircularFrame).ScaleCollection(0).Pointer(0).Value = oldTemp
End If
'Is it the same?
If oldTemp = newTemp Then
oldTemp = newTemp
DirectCast(Me.BaseUI1.Frame(0).FrameCollection(0), NumericalFrame).Indicator.DisplayValue = oldTemp.ToString() & "°"
TMPTimer.Enabled = False
End If
End Sub
My advice is free, and you may get what you paid for.
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When my program first boots up, oldTemp = 0, newTemp = 84, newTemp is the current temperature
in my home town. The guage starts moving from 0 to 84. Now oldtemp = newTemp and the DirectCast statement gets executed. Now I change my zipcode to somewhere in Alaska, newTemp = 54, seeing oldTemp = 84, the guage starts moving backwards till it gets to 54 and and the DirectCast statement gets executed.
My code works just as it is suppose to. So far I have not had any exceptions popup on me and I have checked it with multiple zipcodes. The temperature, wind direction and wind speed guages all move
to thier correct temp, wind direction, and wind speed integers that are retrieved from yahoo.
rspercy
If "You wash your feet and find a pair of socks " Then
"You ARE a Redneck"
End If
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You know what, I read your code wrong. Sorry about that. You are right, your code will work nicely.
My advice is free, and you may get what you paid for.
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Dear friends
I need help, I'm developing a VB.net -SQL server 2000 application VB.net 2008 but i cannot connect Excel by the code:
Dim xlapp As Microsoft.Office.Tools.
or
Dim xlapp As Microsoft.Office.Interop.
'ExcelApplication doesn' appear by autocomplete
knowing that i added the Microsoft excel object library 11 and downloaded the PIA application
I have:
Microsoft Visual Studio Team System 2008
.Net Framework 3.5
Is my application incomplete
if i should use OLE DB please guide me how to Import and Export to an existant excel file
ezzat oraby
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Hi Experts,
I want the code to fetch the last record of customer . I had written the code but it gives error when there is no record found in the table for the requested customer . Please help.
Thanking you,
My Code is ....
rss.Open("select max(orderno) As ono from measurementpant where custno='" & txtcustno.Text & "' AND length<>0 ")
no = Convert.ToInt32(rss.Fields("ono").Value) // here gives error
rss.Close()
rssearch.Open("select * from measurementpant where custno='" & txtcustno.Text & "' AND orderno='" & no & "' ", con, ADODB.CursorTypeEnum.adOpenDynamic, ADODB.LockTypeEnum.adLockPessimistic)
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Two possible options are:
1. check that the record count is greater than 0.
2. use Integer.TryParse() to do the conversion.
1 will tell you that there are no records for customer.
2 will tell you that it could not convert to integer - there may be a record but the field does not contain something that can be converted.
Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis
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hi friend try this code:
Public Function GetMaxVal(ByVal TableN As String, ByVal FieldN As String)
If ConSql.State = ConnectionState.Closed Then ConSql.Open()
Dim CmdSqlGetMax As New SqlCommand("Select Max(" & FieldN &") _
As MaxVal From " & TableN, ConSql)
If Not DBNull.Value.Equals(CmdSqlGetMax.ExecuteScalar) Then
GetMaxVal = CmdSqlGetMax.ExecuteScalar
Else
GetMaxVal = 0
End If
End Function
I used the If statement to escape from the DBNull Hell, If cannot do you may use try .. Catch .. End Try to do
Good Luck
ezzat oraby
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Hi,
Thanks but i want the code for Ms-access database
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Third option, add an ISNULL function to your query;
SELECT ISNULL(MAX(orderno), 0) AS ono
FROM measurementpant
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Sorry bro
SELECT ISNULL(MAX(orderno), 0) AS ono
FROM measurementpant
I suggest it may be
<pre>SELECT NOT ISNULL(MAX(orderno), 0) AS ono </pre>
<pre> FROM measurementpant</pre>
Tell me if wrong
ezzat oraby
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I just ran them on SQL Server, with these results;
SELECT ISNULL(MAX(orderno), 0) AS ono
FROM measurementpant
-- Result for an empty table: '0'
SELECT ISNULL(MAX(orderno), 0) AS ono
FROM measurementpant
-- Result for a table with two tuples: '2'
SELECT NOT ISNULL(MAX(orderno), 0) AS ono
FROM measurementpant
-- Result: Incorrect syntax near the keyword 'NOT'.
Zizo_nis wrote: Tell me if wrong
Your SQL did not compute.
"Some mainframe users still wonder if SQL Server is reliable enough for them. We're a nuclear power plant—how much more reliable do they need it to be?"
-- Janice Hoerber[ ^]
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Hi,
Thanks, But it gives syntax error
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AjitMourya wrote: But it gives syntax error
My apologies, didn't try it on MSAccess. Here is the Access version;
SELECT IIf(IsNull(Max([orderno])), 0, Max([orderno])) AS ono
FROM measurementpant;
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Hi ,
Thanks for sending the code but it gives an error
[Microsoft][ODBC Microsoft Access Driver] Wrong number of arguments used with function in query expression 'isnull (max(orderno),0)'.
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The problem is that if your query does not return any results, there will be no rows, and therefore no value can be assigned to your integer.
Using ISNULL, will not necessarily work either. It also can return zero rows.
So you can either count the rows after AjitMourya wrote: rss.Open("select max(orderno) As ono from measurementpant where custno='" & txtcustno.Text & "' AND length<>0 ")
and before
AjitMourya wrote: no = Convert.ToInt32(rss.Fields("ono").Value)
or you can force a result in your query, and then take that into account when you assign the value to your integer:
rss.Open("select (1 + ISNULL(max(orderno),0)) As ono from measurementpant where custno='" & txtcustno.Text & "' AND length<>0 ")
no = (Convert.ToInt32(rss.Fields("ono").Value) - 1)
My advice is free, and you may get what you paid for.
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HI
I am new to coding and I was in need of a little help.
I have a contacts form and there is a textbox "tbNewContact.Text" and two buttons. When one buttone is pressed I was wanting the following to happen. An sql connection has been opened at form_load.
When the user enters a contacts name it does a check on the database table. If it returns any rows then it displays a message.
If not rows returned then it will submitted the contact to the SQL database.
But it does not work. I get the message "Contacted Added" but nothing has been.
If the code is cra then sorry like i said Im new to this. 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddContact.Click
'Check Contacts
Dim SQLSearch As SqlCommand = sqlconn.CreateCommand
Dim sqlinsert As SqlCommand = sqlconn.CreateCommand
SQLSearch.CommandText = "SELECT * FROM Contacts WHERE ContactName = '%" & tbNewContact.Text & "%';"
Dim SQLDR As SqlDataReader = SQLSearch.ExecuteReader
If SQLDR.HasRows Then
MsgBox("That contact name already exists." & tbNewContact.Text & _
"If you wish to add this contact, please cancel and choose 'Add Existing Contact'", MsgBoxStyle.Information)
SQLDR.Close()
Else
sqlinsert.CommandText = "insert into contacts (contactName) values '%" & tbNewContact.Text & "%';"
MsgBox("Contact Added")
Exit Sub
End If
SQLDR.Close()
End Sub
Thansk In advance
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The error is here:
sqlinsert.CommandText = "insert into contacts (contactName) values '%" & tbNewContact.Text & "%';"
You should change it to:
sqlinsert.CommandText = "insert into contacts (contactName) values ('" & tbNewContact.Text & "');"
Also note that opening the connection at form startup and keeping it open is not a good idea. It may time out or suffer from other connection problems.
You should open a connection each time you need to access the db, and then close it.
Do not worry about opening too many connections, since you will not: pooling and re-using of existing connections is done at driver level.
2+2=5 for very large amounts of 2
(always loved that one hehe!)
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Hi
Thanks for your responce but that does not seem to work either? 
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As a try, you may check
dim My_Value as string=trim(tbNewContact.text.tostring)
And
sqlinsert.CommandText = "insert into contacts (contactName) values '%" & My_Value & "%'
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