I know that that ConfigurationManager.AppSettings("ADOConnectionString") gives the right location for my connection, and family_id is the number 6 (at family_id=6 I know I have the right data in my Product table) so why won't this run past execute reader?
Dim sqlConnection1 As New SqlConnection(ConfigurationManager.AppSettings("ADOConnectionString"))
Dim cmd As New SqlCommand
Dim reader As SqlDataReader
cmd.CommandText = "SELECT * FROM [TID].[dbo].[Product] WHERE family_id=#family_id"
cmd.Parameters.AddWithValue("#family_id", family_id)
cmd.CommandType = CommandType.Text
sqlConnection1.Open()
reader = cmd.ExecuteReader()
You haven't attached the connection to your command. One way to do that is:
cmd.Connection = sqlConnection1
Another is to do it as part of the SqlCommand constructor:
Dim sql As String
Dim cmd As SqlCommand
Dim reader As SqlDataReader
sql = "SELECT * FROM [TID].[dbo].[Product] WHERE family_id=#family_id"
cmd = new SqlCommand(sql, sqlConnection1)
Related
I am having issues assigning an image to every button according to my database.
My current code:
Dim strsql As String
Dim ImgSQl As Image
Dim con As New SqlConnection("constring")
con.Open()
strsql = "SELECT Image FROM Inventory WHERE ID=#ID"
Dim cmd As New SqlCommand(strsql, con)
ItemID = 1
cmd.Parameters.Add("#ID", SqlDbType.VarChar).Value = ItemID
Dim myreader As SqlDataReader
myreader = cmd.ExecuteReader
myreader.Read()
ImgSQl = myreader("Image")
con.Close()
btn1.Image = ImgSQl
This is the error I'm getting:
Unable to cast object of type 'System.Byte[]' to type 'System.Drawing.Image'
All I had to do was dim as Byte, also adding "()" is really important for it to work. Hope answering my own question helps a VB.net beginner out there.
Dim strsql As String
Dim ImgSql() As Byte
Using con As New SqlConnection("constring")
con.Open()
strsql = "SELECT Image FROM Inventory WHERE ID=#ID"
Dim cmd As New SqlCommand(strsql, con)
ItemID = 1
cmd.Parameters.Add("#ID", SqlDbType.VarChar).Value = ItemID
Dim myreader As SqlDataReader
myreader = cmd.ExecuteReader
myreader.Read()
ImgSql = myreader("Imagen")
Dim ms As New MemoryStream(ImgSql)
btn1.Image = Image.FromStream(ms)
con.Close()
End Using
I am trying to improve performance of an application, I have a case where a common SPROC is being used but is it necessary to fill a DataTable just to set 2 variable values?
Is there anything more efficient?
Dim Conn As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("DB").ConnectionString)
Dim CmdUsers As SqlCommand = New SqlCommand("uspGetUsers", Conn)
CmdUsers.CommandType = CommandType.StoredProcedure
CmdUsers.Parameters.Add(New SqlParameter("#UserName", Session("UserID")))
Dim da As SqlDataAdapter = New SqlDataAdapter
Dim dtUserInfo As DataTable = New DataTable
da = New SqlDataAdapter(CmdUsers)
da.Fill(dtUserInfo)
isParent = dtUserInfo.Rows(0)("IsAdmin")
UserVal = dtUserInfo.Rows(0)("UserVal")
A SqlDataReader is the fastest way to read data from a query. Try the following:
Using conn As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("DB").ConnectionString)
conn.Open()
Using cmd As New SqlCommand("uspGetUsers", conn)
cmd.CommandType = CommandType.StoredProcedure
cmd.Parameters.AddWithValue("#UserName", Session("UserID"))
Using reader As SqlDataReader = cmd.ExecuteReader()
While reader.Read()
isParent = reader("IsAdmin")
UserVal = reader("UserVal")
End While
End Using
End Using
End Using
You may need to parse the data to the correct types.
Also, note the use of Using to automatically dispose of the connection, command and reader objects: http://msdn.microsoft.com/en-GB/library/htd05whh.aspx
I'm trying to simply delete data from my access database on the click of a button..
But can't get it to work.
Dim Cmd2 As OleDbCommand
Dim SQL2 As String
Dim objCmd2 As New OleDbCommand
Dim Con2 = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Privat\dreamware\dreamware_db.mdb")
SQL2 = "DELETE FROM dreamware_db WHERE id='21'"
Cmd2 = New OleDbCommand(SQL2, Con2)
Con2.Open()
objCmd2 = New OleDbCommand(SQL2, Con2)
objCmd2.ExecuteNonQuery()
Con2.Close()
Can someone spot the error?
I write your method without errors:
Dim SQL As String
Dim objCmd As OleDbCommand
Dim Con = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Privat\dreamware\dreamware_db.mdb")
SQL = "DELETE FROM dreamware_db WHERE id='21'"
Con.Open()
objCmd = New OleDbCommand(SQL, Con)
objCmd.ExecuteNonQuery()
Con.Close()
I have this code that populates a datagridview with data from ms access:
Dim con As New OleDbConnection
Dim ds As New DataSet
Dim da As OleDb.OleDbDataAdapter
Dim Sql As String
Sql = "SELECT * FROM myTable WHERE case_no=?"
Try
con.ConnectionString = "PROVIDER=Microsoft.ACE.OLEDB.12.0;Data Source=Sample.accdb;Persist Security Info=True;Jet OLEDB:Database Password=dbadmin2010"
con.Open()
Dim cmd As OleDbCommand = New OleDbCommand(Sql, con)
da.SelectCommand = cmd
cmd.Parameters.AddWithValue("case_no", case_no)
Dim ds As DataSet = New DataSet
da.Fill(ds, "Case Info")
DataGridView1.DataSource = ds.Tables("Case Info")
Catch ex As Exception
MsgBox(ex.Message)
End Try
Now I had just finished creating a query from design view within MS Access itself, is there a way to call that query and retrieve the results to my datagridview?
Just use the query name and set the command type, for example, in addition to what you already have, you can use the following notes:
Try
con.ConnectionString = enter_connection_string_here
con.Open()
cmd.Connection = con
cmd.CommandType = CommandType.StoredProcedure
cmd.CommandText = "NameOfQuery"
da.SelectCommand = cmd
cmd.Parameters.AddWithValue("case_no", case_no)
da.Fill(ds, "Case Info")
I've managed to get the following code...
con.ConnectionString = My.Settings.dbConnection
Dim sqlCmd As System.Data.OleDb.OleDbCommand = New System.Data.OleDb.OleDbCommand()
con.Open()
sqlCmd.Connection = con
Dim schemaTable As DataTable
schemaTable = con.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Views, Nothing)
To retrieve a list of Views in my Access database, but now I want to retrieve the results based on a selected View.
Is there a correct method in doing this, or do I take the SQL Statement from the DataTable returned for each row?
Suppose you have Query1 (View) in your Access database (Database1.accdb file). The following code will output each row of the query to the console (for demo purposes):
Dim con As OleDbConnection = New OleDbConnection()
con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Database1.accdb;Persist Security Info=False;"
Dim sqlCmd As OleDbCommand = New System.Data.OleDb.OleDbCommand()
sqlCmd.CommandType = CommandType.StoredProcedure
sqlCmd.CommandText = "Query1"
sqlCmd.Connection = con
con.Open()
Dim reader As OleDbDataReader
reader = sqlCmd.ExecuteReader()
If reader.HasRows Then
While reader.Read()
Console.WriteLine(reader("Column1")) 'output specific column
End While
End If
Console.ReadLine()
Hope this helps