I am using MS Access Database. Now I have to update a particular cell value. Here is my code:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim str As String
Dim Presc As New System.Text.StringBuilder
Dim prs As String(), j As Integer
prs = Split(txtPrescription.Text, vbCrLf)
For j = 0 To prs.Length - 1
Presc.Append(prs(j))
Presc.Append(",")
Next
Try
str = Trim(lsvCase.SelectedItems(0).Text)
'MessageBox.Show(str)
Dim con As System.Data.OleDb.OleDbConnection
Dim ds As New DataSet
Dim rea As System.Data.OleDb.OleDbDataReader
con = New OleDb.OleDbConnection
Dim da As New System.Data.OleDb.OleDbDataAdapter
con.ConnectionString = "Provider = Microsoft.ACE.OLEDB.12.0; Data Source= F:\Sowmya Laptop Backups\sowdb1.accdb;"
con.Open()
Dim cmd As OleDb.OleDbCommand = con.CreateCommand
cmd.CommandText = "UPDATE Casehistory set Prescription =' " & Presc.ToString() & "'"
rea = cmd.ExecuteReader
cmd.ExecuteNonQuery()
da.FillSchema(ds, SchemaType.Mapped)
da.Update(ds, "Casehistory")
con.Close()
Catch ex As Exception
Finally
End Try
End Sub
This code updates all the cells in that column. I want to update only the particular cell having Case_ID = str
Where I have to add the WHERE clause (WHERE Case_ID = " & str & "
I would use command parameters, neater and prevents the SQL injection issue. Something like:
cmd.CommandText = "UPDATE Casehistory set Prescription =#Presc WHERE Case_ID = #CaseID"
cmd.Parameters.AddWithValue("#Presc", Presc.ToString())
cmd.Parameters.AddWithValue("#CaseID",str)
As an aside, having all this code in the button click event is less than ideal. You might want to investigate structuring your app in a more maintainable way - perhaps with a Data Layer for example.
The Where clause should be appended to the end of the OleDbCommmand.CommandText, where you define the Update statement.
Related
I am trying learn how to use Access within VB.NET so i tried to make a simple application using an Access Database that can be used as a dictionary where someone can add some words int the database and then he can search for them.
My db contains two tables one with Word | Description and another one with Word | Synonym
The issue is that one word may have more than one Synonyms so i was thinking i could type all the synonyms in a textbox and using Regex.Split(" ") to split them and insert them in a loop. Can this be done with OleDbParameters?
This is what i have done so far but it only inserts the last record:
str = "insert into Synonyms ([Word],[Synonym]) values (#word,#synonym)"
cmd = New OleDbCommand(str, myConnection)
cmd.Parameters.Add(New OleDbParameter("Word", CType(txtWord.Text,
String)))
cmd.Parameters.Add("#synonym", OleDbType.VarChar)
Dim syn As String() = Regex.Split(txtSynonyms.Text, " ")
Dim i As Integer = 0
While i < syn.Length()
cmd.Parameters("#synonym").Value = syn(i)
i = i + 1
End While
Try
cmd.ExecuteNonQuery()
cmd.Dispose()
MsgBox("Synonyms for word """ & txtWord.Text & """ added")
txtWord.Clear()
txtSynonyms.Clear()
Catch ex As Exception
MsgBox(ex.Message)
End Try
myConnection.Open()
While i < syn.Length()
cmd.Parameters("#synonym").Value = syn(i)
cmd.ExecuteNonQuery()
i = i + 1
End While
myConnection.Close()
Maybe you will find this helpful.
Imports System.Data.OleDb
Public Class Form1
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim con As New OleDb.OleDbConnection
Dim dbprovider As String
Dim dbsource As String
Dim ds As New DataSet
Dim da As OleDb.OleDbDataAdapter
Dim sql As String
Dim inc As Integer
dbprovider = "Provider=Microsoft.ACE.OLEDB.12.0;"
dbsource = "Data Source = C:\your_path_here\Nwind_Sample.accdb"
con.ConnectionString = dbprovider & dbsource
con.Open()
sql = "SELECT * FROM [OrderDetails]"
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(ds, "OrderDetails")
Dim builder As New OleDbCommandBuilder(da)
Dim dsnewrow As DataRow
dsnewrow = ds.Tables("OrderDetails").NewRow()
dsnewrow.Item(0) = OrderID.Text
dsnewrow.Item(1) = ProductID.Text
dsnewrow.Item(2) = UnitPrice.Text
dsnewrow.Item(3) = Quantity.Text
dsnewrow.Item(4) = Discount.Text
'dsnewrow.Item(6) = True
ds.Tables("OrderDetails").Rows.Add(dsnewrow)
da.Update(ds, "OrderDetails")
End Sub
End Class
I have the following code and through debugging the problem begins at the While loop. I am trying to retrieve information from 2 tables and insert it into the table created. The information is not being inserted into the table and I am getting blank rows.
Imports System.Data.OleDb
Public Class RouteToCruise
Private Sub RouteToCruise_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
Private Sub Route_Btn_Click(sender As Object, e As EventArgs) Handles Route_Btn.Click
Dim row As String
Dim connectString As String = "Provider=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=M:\ICT-Group-Project\DeepBlueProject\DeepBlueProject\DeepBlueTables.mdb"
Dim cn As OleDbConnection = New OleDbConnection(connectString)
cn.Open()
Dim CruiseQuery As String = "SELECT CruiseID, RouteID FROM Cruise WHERE CruiseID =?"
Dim RouteQuery As String = "SELECT RouteName FROM Route WHERE RouteID =?"
Dim cmd As OleDbCommand = New OleDbCommand(CruiseQuery, cn)
Dim cmd2 As OleDbCommand = New OleDbCommand(RouteQuery, cn)
cmd.Parameters.AddWithValue("?", Route_Txt.Text)
Dim reader As OleDbDataReader
reader = cmd.ExecuteReader
'RCTable.Width = Unit.Percentage(90.0)
RCTable.ColumnCount = 2
RCTable.Rows.Add()
RCTable.Columns(0).Name = "CruiseID"
RCTable.Columns(1).Name = "Route"
While reader.Read()
Dim rID As String = reader("RouteID").ToString()
cmd2.Parameters.AddWithValue("?", rID)
Dim reader2 As OleDbDataReader = cmd2.ExecuteReader()
'MsgBox(reader.GetValue(0) & "," & reader.GetValue(1))
row = reader("CruiseID") & "," & reader2("RouteName")
RCTable.Rows.Add(row)
cmd.ExecuteNonQuery()
reader2.Close()
End While
reader.Close()
cn.Close()
End Sub
End Class
If I understand your tables structure well then you could just run a single query extracting data from the two table and joining them in a new table returned by the query
Dim sql = "SELECT c.CruiseID c.CruiseID & ',' & r.RouteName as Route " & _
"FROM Cruise c INNER JOIN Route r ON c.RouteID = c.RouteID " & _
" WHERE c.CruiseID = #cruiseID"
Dim cmd As OleDbCommand = New OleDbCommand(sql, cn)
cmd.Parameters.Add("#cruiseID", OleDbType.Int).Value = Convert.ToInt32(Route_Txt.Text)
Dim RCTable = new DataTable()
Dim reader = cmd.ExecuteReader()
reader.Load(RCTable)
At this point the RCTable is filled with the data coming from the two tables and selected using the Route_Txt textbox converted to an integer. If the CruiseID field is not a numeric field then you should create the parameter as of type OleDbType.VarWChar and remove the conversion to integer
Try simplifying your query.
Dim CruiseRouteQuery As String = "SELECT C.CruiseID, C.RoutID, R.Routename FROM Cruise C LEFT JOIN Route R ON C.RouteID = R.RoutID WHERE CruiseID =?"
Also, please let us know what errors you are getting.
I'm writing a calorie counter tool for my girlfriend...
But I've run in to an issue I really cant figure out...
I have place in my script where I would wanna take some information out from my db...
The specific place in the script thats teasing, is the one that will take out data from a row called "antal" from a table called "items".
One place in my script, I call "navn" from items, and it works perfect...
This other place, it gives me the error that there isn't any data in the row!
My code looks so far like this:
Imports System.Data.OleDb
Private Sub ins_kat_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ins_kat.SelectedIndexChanged
Dim Con = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\Privat\MCC\mccdb.mdb")
Con.Open()
Dim command As OleDbCommand = New OleDbCommand("SELECT * FROM items WHERE kat = '" & ins_kat.Text & "' ORDER BY id DESC", Con)
Dim read As OleDbDataReader = command.ExecuteReader()
ins_mad.Items.Clear()
While read.Read()
ins_mad.Items.Add(read.Item("navn")) '<---- This place works!!!
End While
Con.Close()
End Sub
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
Dim ialt_c_counter As String
Dim ialt_c_counter_conv As Decimal
Dim ialt_c_counter_conv2 As Decimal
Dim ialt_counter As String
Dim ialt_final As Decimal
Dim Con = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\Privat\MCC\mccdb.mdb")
Con.Open()
Dim command1 As OleDbCommand = New OleDbCommand("SELECT * FROM food WHERE dag = '" & stat_dag.Text & "' AND maaned = '" & stat_maaned1.Text & "' AND aar = '" & stat_aar1.Text & "'", Con)
Dim read1 As OleDbDataReader = command1.ExecuteReader()
While read1.Read()
ialt_c_counter = read1.Item("antal")
ialt_c_counter_conv = System.Convert.ToDecimal(ialt_c_counter)
Dim commandX As OleDbCommand = New OleDbCommand("SELECT * FROM items", Con)
Dim reader As OleDbDataReader = commandX.ExecuteReader()
ialt_counter = reader.Item("antal") '<--- THIS ONE is giving me the error!!
ialt_c_counter_conv2 = System.Convert.ToDecimal(ialt_counter)
ialt_final = (ialt_c_counter_conv / 100 * ialt_c_counter_conv2) + ialt_final
End While
Con.Close()
MsgBox(ialt_final)
End Sub
End Class
By now, I want a MsgBox telling me the result of my algorithm, but I don't even get that far cause of the error message...
I guess the error you see is
InvalidOperationException: Invalid attempt to read when no data is present.
You never call Read() on the OleDbDataReader called reader.
Note how you use a While loop to call Read() for read and read1, but not reader (bad variable names, btw).
I have problem with data that needs to be seen on datagridview. Bellow is my code:
Public Class Form3
Private Sub Form3_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim CONNECT_STRING As String = (...)
Dim cnn As New OleDbConnection(CONNECT_STRING)
cnn.Open()
MsgBox(status_narocila.value)
Dim sql As String = "SELECT artikel.st_artikla, artikel.naziv_artikla, narocilo.kolicina, narocilo.barva_tiska, narocilo.izvedba, narocilo.opombe, narocilo.datum_narocila, narocilo.rok_izdelave, narocilo.status, narocilo.ID FROM (narocilo INNER JOIN artikel ON narocilo.id_artkla = artikel.ID) WHERE(narocilo.ID = '" & status_narocila.value & "')"
Dim cmd As New OleDbCommand(sql, cnn)
Dim da As New OleDbDataAdapter(cmd)
Dim ds As New DataSet
da.Fill(ds, "artikel")
cnn.Close()
DataGridView1.DataSource = ds.Tables("artikel")
End Sub
End Class
Value status.narocila.value is integer, I've tested it and getting right value from it. The code is working fine without WHERE clause.
= '" & status_narocila.value & "')"
should be
= " & status_narocila.value & ")"
no ' on numeric data types.
If narocilo.ID is also an integer, then the problem is you're using text qualifers on an integer field.
Try changing your WHERE clause to:
WHERE(narocilo.ID = " & status_narocila.value & ")"
I have a table in MS Access which has a colum named NameC (using ODBC to connect to MS Access)
I want the result of the following query to be saved in a txtField
Dim query = "SELECT NameC FROM Table WHERE ClientID = " & Integer.Parse(clientID)
How to do that in VB.NET?
I have a txtNameC.Text field
I currently was reviewing some sample code and they do:
Dim _consultationTable As DataTable
Public Sub Load()
Dim query = "SELECT * FROM Table WHERE ClientID = " & Integer.Parse(clientID)
Me._consultationTable = DatabaseFunctions.GetDataTable(query)
dvgInfo.Rows.Clear()
For Each dtRow In Me._consultationTable.Rows
dvgInfo.Rows.Add()
dvgInfo.Rows.Add(dvgInfo.RowCount-1).Cells("ColClientID").Value = dtRow("ClientId").ToString()
Next
but I do not want to fill a table I just want to get the result of a query into a text box
How can I do this?
I want to do something like this but just return a value and save it into a textbox
Protected Sub BindData()
strSQL = "SELECT * FROM customer"
Dim dtReader As OdbcDataReader
objCmd = New OdbcCommand(strSQL, objConn)
dtReader = objCmd.ExecuteReader()
'*** BindData to GridView ***'
myGridView.DataSource = dtReader
myGridView.DataBind()
dtReader.Close()
dtReader = Nothing
End Sub
Protected Sub BindData()
strSQL = "SELECT SpecificValue FROM customer where x = y..."
Dim dtReader As OdbcDataReader
objCmd = New OdbcCommand(strSQL, objConn)
dtReader = objCmd.ExecuteReader()
'*** BindData to GridView ***'
myGridView.DataSource = dtReader
myGridView.DataBind()
dtReader.Close()
dtReader = Nothing
End Sub
use DataReader.populate ur data from database in the datareader & from the the datareader u can use perticular values.
i don't know your code,that's why i m giving one simple example.
here is one example.
imports System.Data.OleDb
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim connetionString As String
Dim oledbCnn As OleDbConnection
Dim oledbCmd As OleDbCommand
Dim sql As String
connetionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Your mdb filename;"
sql = "Your SQL Statement Here like Select * from product"
oledbCnn = New OleDbConnection(connetionString)
Try
oledbCnn.Open()
oledbCmd = New OleDbCommand(sql, oledbCnn)
Dim oledbReader As OleDbDataReader = oledbCmd.ExecuteReader()
While oledbReader.Read
MsgBox(oledbReader.Item(0) & " - " & oledbReader.Item(1) & " - " & oledbReader.Item(2))
End While
oledbReader.Close()
oledbCmd.Dispose()
oledbCnn.Close()
Catch ex As Exception
MsgBox("Can not open connection ! ")
End Try
End Sub
End Class