I would like to fire an SQL Query from my ASP.NET page (vb), what the query will do is to look for the maximum value from a column and then return that value and place it into a label in the webpage.
Currently i dont know to fire the SQL command and then return with the value, a correction to my code is hihgly appreciated.
Dim Con As New SqlConnection
Dim SQL As String
Con.ConnectionString = "Data Source=WCRDUSMJEMPR9\SQLEXPRESS;Initial Catalog=MicroDB;Integrated Security=True"
Con.Open()
SQL = "SELECT MAX(ID_ControlCharts) FROM ControlCharts"
Label123.Text = SQL
The code above is not working, i know that i need to execute the query however i'm totally lost.
You need to create sql command and call executescalar method.
Ex:
Dim Con As New SqlConnection
Dim SQL As String
Con.ConnectionString = "Data Source=WCRDUSMJEMPR9\SQLEXPRESS;Initial
Catalog=MicroDB;Integrated Security=True"
Con.Open()
Dim cmd as new SQLCommand(sql,Con)
Dim obj = cmd.ExecuteScalar()
if(obj!=null)
Label123.Text = obj.ToString()
end if
Con.Close()
Dim com as SqlCommand = Con.CreateCommand
Label123.Text = com.ExecuteScalar(SQL)
Related
i am trying to get data from ms access database using this code but i can not this is my code is this correct
Dim query As String = "SELECT [data] FROM tabless WHERE user = '" & user.Text & "'"
Using connection As New OleDbConnection(connectionString)
Dim cmd As New OleDbCommand(query)
Dim adapter As OleDbDataAdapter = New OleDbDataAdapter(query, connection)
Dim com As New OleDbCommand(query, connection)
connection.Open()
'on the line below I get an error: connection property has not been initialized
Dim reader As OleDbDataReader = cmd.ExecuteReader()
While reader.Read()
Label1.Text = (reader(0).ToString())
End While
reader.Close()
End Using
Database
|data|
asl
trying to get data from database and trying to show it in a label is this possible
You never associated cmd with the connection, and you never use com or adapter. This is the sort of thing you can figure out by stepping through your code line by line and inspecting the state of it.
Dim query As String = "SELECT [data] FROM tabless WHERE user = '" & user.Text & "'"
Using connection As New OleDbConnection(connectionString)
Dim cmd As New OleDbCommand(query, connection)
connection.Open()
Dim reader As OleDbDataReader = cmd.ExecuteReader()
While reader.Read()
Label1.Text = (reader(0).ToString())
End While
reader.Close()
End Using
Also, your code is vulnerable to a SQL Injection Attack. You should not be concatenating strings together to form your queries. You should instead use parameterized queries.
I am trying to save data to an mdf file which has been detached from SQL server and added to my APP_DATA folder in Solution Explorer, but I am unable do that. Your help will be appreciated. Thank you! Here is my code:
Dim con As New SqlConnection
Dim cmd As New SqlCommand
Dim EmployeeNo As Integer
Dim EmployeeName As String
Dim SupervisorName As String
Dim DateCreated As Date
Dim WeekRange As String
Dim MonthRange As String
Dim ScheduleIn As String
Dim ScheduleOut As String
Dim WorkStatus As String
EmployeeNo = EmpNoText.Text
EmployeeName = EmpNameText.Text
SupervisorName = TeamLeadDropDown.Text
DateCreated = DateCreatedTextBox.Text
WeekRange = WeekRangeTextBox.Text
MonthRange = MonthDropDown.Text
ScheduleIn = ScheduleInBox.Text
ScheduleOut = ScheduleOutBox.Text
WorkStatus = StatusDropDown.Text
Try
con.ConnectionString = "Data Source=(LocalDB)\v11.0;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\DATA\JIBKPI.mdf;Initial Catalog=JIBKPI;Integrated Security=True"
con.Open()
cmd.Connection = con
cmd.CommandText = "INSERT INTO AgentAttendance ([EmployeeNo], [EmployeeName], [SupervisorName], [DateCreated], [WeekRange], [MonthRange], [ScheduleIn], [ScheduleOut], [WorkStatus]) VALUES (#EmployeeNo, #EmployeeName, #SupervisorName, #DateCreated, #WeekRange, #MonthRange, #ScheduleIn, #ScheduleOut, #WorkStatus,)"
cmd.ExecuteNonQuery()
MsgBox("Successfuly saved!", MsgBoxStyle.Information + MsgBoxStyle.OkOnly)
Catch ex As Exception
MsgBox("Error: Unable to save data.")
Finally
con.Close()
End Try
In my web.config the connection string is:
<connectionStrings>
<add name="JIBKPIConnectionString" connectionString="Data Source=(LocalDB)\v11.0;AttachDbFilename="C:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\DATA\JIBKPI.mdf";Initial Catalog=JIBKPI;Integrated Security=True" providerName="System.Data.SqlClient"/>
Looking at your code, first thing I notice is that you're using parameters in your query:
cmd.CommandText = "INSERT INTO AgentAttendance ([EmployeeNo], [EmployeeName], [SupervisorName], [DateCreated], [WeekRange], [MonthRange], [ScheduleIn], [ScheduleOut], [WorkStatus]) VALUES (#EmployeeNo, #EmployeeName, #SupervisorName, #DateCreated, #WeekRange, #MonthRange, #ScheduleIn, #ScheduleOut, #WorkStatus,)"
But nowhere have you actually set those parameters. So before you execute your query you need to create those parameters. Something like:
cmd.Parameters.Add("#EmployeeNo", SqlDbType.Int)
command.Parameters("#EmployeeNo").Value = EmployeeNo
etc...
Then execute your query:
cmd.ExecuteNonQuery()
Also, if you're going to use the connection string in your web.config, remove both the " from the AttachDbFilename
Change this:
AttachDbFilename="C:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\DATA\JIBKPI.mdf"
to this:
AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\DATA\JIBKPI.mdf
EDIT: remove the last comma from your query after #WorkStatus
#WorkStatus,)"
becomes
#WorkStatus)"
I have the below stored procedure in SQL Server 2008 which is not generating any errors in SQL, but is generating one in the web application which states "'GetGenInfo_Delete01_01_22' expects parameter '#FPath', which was not supplied". I am fairly novice at SQL, but what I am trying to do is return a field to VB.NET before the row is deleted. Any suggestions would be very helpful.
ALTER Procedure [dbo].[GetGenInfo_Delete01_01_22]
#IDX int,
#FPath varchar(100) OUTPUT
AS
Begin
SELECT #FPath = (SELECT FilePath FROM GenInfo_E1_01_22 Where ID=#IDX)
DELETE
FROM GenInfo_E1_01_22
WHERE ID = #IDX
END
Here is the VB code calling the stored proc
Using con As New SqlConnection(connstr)
Using cmd As New SqlCommand()
cmd.CommandType = CommandType.StoredProcedure
cmd.CommandText = "GetGenInfo_Delete01_01_22"
cmd.Parameters.Add("IDX", ID)
Dim returnParameter = cmd.Parameters.Add("#FPath", SqlDbType.VarChar)
returnParameter.Direction = ParameterDirection.ReturnValue
cmd.Connection = con
con.Open()
GridView1.DataSource = cmd.ExecuteReader()
GridView1.DataBind()
con.Close()
End Using
End Using
You're creating parameter returnParameter, but you're not adding it to the parameters collection. Use cmd.Parameters.Add(returnParameter) prior to DB Call.
You could add an FPath parameter to cmd. Do it like this:
SqlParameter fpath = new SqlParameter();
fpath.Direction = ParameterDirection.Output;
fpath.ParameterName = "#FPATH";
cmd.Parameters.Add(p);
I have a form which goes to the following login script when it is submitted.
<%
Dim myConnection As System.Data.SqlClient.SqlConnection
Dim myCommand As System.Data.SqlClient.SqlCommand
Dim requestName As String
Dim requestPass As String
requestName = Request.Form("userName")
requestPass = Request.Form("userPass")
Dim queryString As String = "SELECT COUNT(*) AS Num_Of_User FROM tblusers WHERE username='" & requestName & "' AND password='" & requestPass & "'"
myConnection = New System.Data.SqlClient.SqlConnection("Data Source=(local);InitialCatalog=dbtest;Integrated Security=True")
myCommand = New System.Data.SqlClient.SqlCommand(queryString, myConnection)
myConnection.Open()
Dim reader As System.Data.SqlClient.SqlDataReader = myCommand.ExecuteReader()
%>
Now in theory, I should be able to get that Num_Of_User from the SQL Query and if it equals 1 than the login was successful. Is this the correct way? And how can I get the value that the SQL returns?
You are wide open to SQL injection using that code.
See happens if you enter the username as ' OR 2>1--
You need to change the to use a parametrized query.
Dim queryString As String = "SELECT COUNT(*) AS Num_Of_User FROM tblusers WHERE username=#username AND password=#password"
myConnection = New System.Data.SqlClient.SqlConnection("Data Source=(local);InitialCatalog=dbtest;Integrated Security=True")
myCommand = New System.Data.SqlClient.SqlCommand(queryString, myConnection)
myCommand.Parameters.AddWithValue("#username", requestName)
myCommand.Parameters.AddWithValue("#password", requestPass)
Also you are not handling any exceptions that might be thrown, nor disposing your objects.
Your code should look more like the following.
Dim numUsers as Integer
Using myConnection as New System.Data.SqlClient.SqlConnection("Data Source=(local);InitialCatalog=dbtest;Integrated Security=True")
Dim queryString As String = "SELECT COUNT(*) AS Num_Of_User FROM tblusers WHERE username=#username AND password=#password"
Using myCommand as New System.Data.SqlClient.SqlCommand(queryString, myConnection)
myConnection.Open
myCommand.Parameters.AddWithValue("#username", requestName)
myCommand.Parameters.AddWithValue("#password", requestPass)
numUsers = myCommand.ExecuteScalar()
End Using
End Using
The above code will make sure your objects are disposed, but won't handle any exceptions that might be thrown.
Try myCommand.ExecuteScalar(), which returns the value from the first column in the first row of the resultset - exactly the value you're after here.
Also, check into the ASP.Net 'built in' authentication methods - this might save you some effort.
I have this mySQL code that connects to my server. It connects just fine:
Dim MyConString As String = "DRIVER={MySQL ODBC 3.51 Driver};" & _
"SERVER=example.com;" & _
"DATABASE=xxx;" & _
"UID=xxx;" & _
"PASSWORD=xxx;" & _
"OPTION=3;"
Dim conn As OdbcConnection = New OdbcConnection(MyConString)
conn.Open()
Dim MyCommand As New OdbcCommand
MyCommand.Connection = conn
MyCommand.CommandText = "select * from userinfo WHERE emailAddress = '" & theUN & "'""
MyCommand.ExecuteNonQuery()
conn.Close()
However, i have an old Classic ASP page that uses "oRecordset" to get the data from the mySQL server:
Set oConnection = Server.CreateObject("ADODB.Connection")
Set oRecordset = Server.CreateObject("ADODB.Recordset")
oConnection.Open "DRIVER={MySQL ODBC 3.51 Driver}; SERVER=example.com; PORT=3306; DATABASE=xxx; USER=xxx; PASSWORD=xxx; OPTION=3;"
sqltemp = "select * from userinfo WHERE emailAddress = '" & theUN & "'"
oRecordset.Open sqltemp, oConnection,3,3
And i can use oRecordset as follows:
if oRecordset.EOF then....
or
strValue = oRecordset("Table_Name").value
or
oRecordset("Table_Name").value = "New Value"
oRecordset.update
etc...
However, for the life of me, i can not find any .net code that is similar to that of my Classic ASP page!!!!!
Any help would be great! :o)
David
This is what you have to do:
instead of MyCommand.ExecuteNonQuery you should use MyCommand.ExecuteQuery and assign it to DataReader.
Check out this sample:
Dim myConnection As SqlConnection
Dim myCommand As SqlCommand
Dim dr As New SqlDataReader()
'declaring the objects
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)_
Handles MyBase.Load
myConnection = New SqlConnection("server=localhost;uid=sa;pwd=;database=pubs")
'establishing connection. you need to provide password for sql server
Try
myConnection.Open()
'opening the connection
myCommand = New SqlCommand("Select * from discounts", myConnection)
'executing the command and assigning it to connection
dr = myCommand.ExecuteReader()
While dr.Read()
'reading from the datareader
MessageBox.Show("discounttype" & dr(0).ToString())
MessageBox.Show("stor_id" & dr(1).ToString())
MessageBox.Show("lowqty" & dr(2).ToString())
MessageBox.Show("highqty" & dr(3).ToString())
MessageBox.Show("discount" & dr(4).ToString())
'displaying the data from the table
End While
dr.Close()
myConnection.Close()
Catch e As Exception
End Try
HTH
Dim conn As OdbcConnection = New OdbcConnection("DRIVER={MySQL ODBC 3.51 Driver}; SERVER=xxx.com; DATABASE=xxx; UID=xxx; PASSWORD=xxx; OPTION=3;")
conn.Open()
Dim MyCommand As New OdbcCommand
MyCommand.Connection = conn
MyCommand.CommandText = "SELECT * FROM userinfo"
Dim rst = MyCommand.ExecuteReader()
While rst.Read()
response.write(rst("userID").ToString())
End While
conn.Close()
Dim email As String = "anyone#anywhere.com"
Dim stringValue As String
Using conn As OdbcConnection = New OdbcConnection(MyConString)
conn.Open()
Dim sql = "Select ... From userInfo Where emailAddress = #Email"
Using cmd As OdbcCommand = New OdbcCommand(sql, conn)
cmd.Parameters.AddWithValue("#Email", email)
Dim reader As OdbcDataReader = cmd.ExecuteReader()
While reader.Read()
stringValue = reader.GetString(0)
End While
End Using
conn.Close()
End Using
'To do an Update
Using conn As OdbcConnection = New OdbcConnection(MyConString)
conn.Open()
Dim sql As String = "Update userInfo Set Column = #Value Where PK = #PK"
Using cmd As OdbcCommand = New OdbcCommand(sql, conn)
cmd.Parameters.AddWithValue("#Email", email)
cmd.ExecuteNonQuery()
End Using
End Using
'To do an Insert
Using conn As OdbcConnection = New OdbcConnection(MyConString)
conn.Open()
Dim sql As String = "Insert userInfo(Col1,Col2,...) Values(#Value1,#Value2...)"
Using cmd As OdbcCommand = New OdbcCommand(sql, conn)
cmd.Parameters.AddWithValue("#Col1", value1)
cmd.Parameters.AddWithValue("#Col2", value2)
...
cmd.ExecuteNonQuery()
End Using
End Using
First, even in ASP Classic, it is an absolutely horrid approach to concatenate a value directly into a SQL statement. This is how SQL Injection vulnerabilities happen. You should always sanitize values that get concatenated into SQL statements. In .NET, you can use parametrized queries where you replace the values that go into your query with a variable that begins with an # sign. You then add a parameter to the command object and set your value that way. The Command object will sanitize the value for you.
ADDITION
You mentioned in a comment that your ASP Classic code is shorter. In fact, the .NET code is shorter because there are a host of things happening that you do not see and have not implemented in your ASP Classic code. I already mentioned one which is sanitizing the inputs. Another is logging. Out of the box, if an exception is thrown, it will log it in the Event Log with a call stack. To even get a call stack in ASP Classic is a chore much less any sort of decent logging. You would need to set On Error Resume Next and check for err.number <> 0 after each line. In addition, without On Error Resume Next, if an error is thrown, you have no guarantee that the connection will be closed. It should be closed, but the only way to know for sure is to use On Error Resume Next and try to close it.
Generally, I encapsulate all of my data access code into a set of methods so that I can simply pass the SQL statement and the parameter values and ensure that it is called properly each time. (This holds true for ASP Classic too).