Incorrect Syntax After Server Up For A Few Days

Dear All,

My VB.Net application connects to MSSQL. It is always running fine for a few days, but encounters "incorrect syntax" as following unless the server is restarted.

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Exception occurred System.Runtime.InteropServices.COMException (0x80040E14): Line 1: incorrect syntax near 'CDO'.
at ADODB.ConnectionClass.Execute (String CommandText, Object& RecordsAffected, Int32 Options)
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There are a few applications in the server. If certain service is stopped, my program continues to run. So I am sure that the MSSQL connections have been taken up, which causes the error. How to prove it? And is there any way to reserve some DB connections to a particular application only?

Thanks for any hint!

I attach my codes below. Anything wrong with the way that I handled the ADODB?


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Public Sub SendAllEmails()
Try
Dim cn As ADODB.Connection = openConn()
Dim rs As ADODB._Recordset
Dim rs2 As ADODB._Recordset
sqlstmt = "select * FROM EMAILTABLE"
rs = cn.Execute(sqlstmt)

While Not rs.EOF

Dim MAIL_ADD_USED As String = rs.Fields("MAIL_ADD_USED").Value.ToString

sqlstmt = "select * from NAMETABLE where EMAIL = '" & MAIL_ADD & "'"
rs2 = cn.Execute(sqlstmt)


If Not rs2.EOF And ErrMsg = "" Then

ErrMsg = SendMail(MAIL_ADD, REPORT_TITLE)

If Not ErrMsg Is Nothing And ErrMsg.Equals("Success") Then
MAIL_DATE_SENT = Now.ToString
MAIL_STATUS = "S"

'wait to make sure the email is sent
System.Threading.Thread.Sleep(1000 * 30)
Else
MAIL_STATUS = "F"
End If

End If

rs2.Close()

sqlstmt = "update EMAILTABLE set " & _
" MAIL_STATUS = " & MAIL_STATUS & "," & _
" MAIL_ERRMSG = null" & _
" where EMAIL = " & MAIL_ADD

cn.Execute(sqlstmt)

rs.MoveNext()

End While

rs.Close()
cn.Close()

Catch e As Exception
EventLog1.WriteEntry("Exception: " & e.ToString)
End Try

End Sub
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