I am developing a VB.NET ASPX file. This report is currently working but now I want to add a parameter which should be an array list displaying all records from below SQL query:
" select distinct instrument_name AS instrument_name from FRUD.tblXref order by instrument_name "
But this array list displays "System.Data.Common" for all possible values from code:
Sub Main()
Dim pcSQL As String
Dim ProductList As New ArrayList()
pcSQL = " select distinct instrument_name AS instrument_name from FRUD.tblXref order by instrument_name "
Dim DBConn As SqlConnection
DBConn = New SqlConnection(ConfigurationManager.AppSettings("AMDMetricsConnectionString"))
DBConn.Open()
Dim reader As SqlDataReader
Dim DBCommand As New SqlCommand(pcSQL, DBConn)
reader = DBCommand.ExecuteReader()
dProdCodeSearch.DataSource = reader
dProdCodeSearch.DataBind()
reader.Close()
I am sure I am doing something wrong which is a really simple fix. This SQL Connection works for my data tables in this report. But this is only parameter that I set to SQL output.
You need to create a Collection that is storing the values from the database and then read those values into an array. Something like
Dim instrumentNames As New List(Of String)
While reader.Read()
instrumentNames.Add(reader.GetString("insturment_name"))
End While
dProdCodeSearch.DataSource = insturmentNames
Related
Dim da As New OleDb.OleDbDataAdapter("SELECT ITemID, ItemName, ItemDescription, ItemQuantity, ItemBorrowedDate, ItemReturnDate FROM BorrowedItem order by ID DESC", conn)
Dim dt As New DataTable
da.Fill(dt)
OverDueList.DataSource = dt.DefaultView
Dim ItemReturenedDate As New Date
Dim DateToday As Integer
Dim DateDiff As New Date
ItemReturenedDate = dt.Rows(0)("ItemReturnDate")
DateDiff = DateDiff(DateInterval.Day, ItemReturenedDate, DateTimePicker1.Value)`
I tried that code to generate output but my knowledge was not that good. i need help, it could be a great help if someone would notice it
And if you looking to send all rows to say a grid?
then this:
Dim strSQL As String =
"Select ITemID, ItemName, ItemDescription, ItemQuantity, ItemBorrowedDate, ItemReturnDate,
(ItemReturnDate - ItemBorroedDate) as MyDays
FROM BorrowedItem order by ID DESC"
dim dt as DataTable = MyRst(strSQL)
So, you can return MyDays for each row, and then say send the data table to a data grid view.
And I get VERY tired very fast typing over confection string and command objects, so you can use this routine (over and over).
Function MyRst(strSQL As String) As DataTable
Dim rstData As New DataTable
Using conn As New OleDbConnection(My.Settings.AccessDB)
Using cmdSQL As New OleDbCommand(strSQL, conn)
conn.Open()
rstData.Load(cmdSQL.ExecuteReader)
End Using
End Using
Return rstData
End Function
Try something like this:
Dim ItemReturenedDate As Date
Dim Days As Long
ItemReturenedDate = dt.Rows(0)("ItemReturnDate")
Days = DateTimePicker1.Value.Subtract(ItemReturenedDate).TotalDays
I am trying to create a system that will load items from a database. There are two comboboxes; combobox1 which loads items from database table 1 and combox2 which loads items from database table 2.
Both tables are in the same database.
Here is was I tried but when I run the system I get this error:
(Conversion from string "SELECT * FROM dbo.Dishes" to type 'Long' is not valid.)
Here is the code I'm using:
Dim connection As New SqlConnection("Server = DESKTOP-1373H91; Initial Catalog = MealPreOrderSystem; Integrated Security = True")
connection.Open()
Dim query As String = "SELECT * FROM dbo.Dishes" And "SELECT * FROM dbo.Desserts"
Dim cmd As SqlCommand
cmd = New SqlCommand(query, connection)
Dim reader As SqlDataReader
reader = cmd.ExecuteReader
While reader.Read
cbxType.Items.Add(reader.Item("MealName"))
cbxType.Items.Add(reader.Item("DessertName"))
End While
connection.Close()
In VB.NET,AND is an operator.It is used to perform conjunction between either Booleans or Integers/Doubles/any numeric expression.Lets take your query string as an example :
Dim query As String = "SELECT * FROM dbo.Dishes" And "SELECT * FROM dbo.Desserts"
You are using AND here to join 2 sentences/strings which wouldn't result in anything rather it is trying to cast it as a Long.
Try to execute this command in SQL and you won't find any luck :(.
Your statements are correct :
SELECT * FROM dbo.Dishes
SELECT * FROM dbo.Desserts
But the way you are trying to achieve your goals is incorrect :(.
To get the data from the database into your combobox, what you can do is either use two comboboxes with separated SQL Queries/SQL Commands or you can use one combobox where you add data from both the databases but separate them with some special characters such as a comma ,
A sample may look like :
With one combobox
Dim cmd1 as new SqlCommand("SELECT * FROM dbo.Dishes",connection)
Dim dr as SqlDatareader = cmd1.ExecuteReader
While dr.Read
mycombo1.Items.Add(dr(0)) ' Here 0 is the column count,change it as required
End while
Dim cmd2 as new SqlCommand("SELECT * FROM dbo.Desserts",connection)
Dim dr2 as SqlDatareader = cmd2.ExecuteReader
While dr2.Read
mycombo2.Items.Add(dr2(0)) ' Here 0 is the column count,change it as required
End while
With 1 combobox
Here it gets a bit complicated.Firstly you need to populate your combobox from the data received from the first dataReader.Then, when the 2nd datareader is reading the data , you need to update the existing data/Item of the combobox keeping the existing data/item but adding new data/item to each existing data/item(separating them with ,).
Sample :
Dim i as Integer
Dim cmd1 as new SqlCommand("SELECT * FROM dbo.Dishes",connection)
Dim dr as SqlDatareader = cmd1.ExecuteReader
While dr.Read
mycombo1.Items.Add(dr(0))
End while
Dim cmd2 as new SqlCommand("SELECT * FROM dbo.Desserts",connection)
Dim dr2 as SqlDatareader = cmd2.ExecuteReader
While dr2.Read
mycombo1.Items(i) = myconbo1.Items(i) & "," & dr2(0)
i = i + 1
End while
Now, NOTE THAT I AM USING MULTIPLE DATAREADERS WITH THE SAME CONNECTION ,SO YOU MAY NEED TO INCLUDE MultipleActiveResultSets=True IN YOUR CONNECTION STRING or ENCLOSE THE DATAREADERS IN USING STATEMENTS or CALL dataReader.Close AFTER EACH DATAREADER HAS COMPLETED READING FROM THE DATABASE
This will solve your issue :)
Looks like you don't know how to write SQL queries (and your VB syntax itself looks faulty - string AND string?).
Dim connection As New SqlConnection("Server = DESKTOP-1373H91; Initial Catalog = MealPreOrderSystem; Integrated Security = True")
Dim query As String = <cmdString>
SELECT MealName as Name FROM dbo.Dishes
union
SELECT DessertName as Name FROM dbo.Desserts
</cmdString>
Dim cmd As SqlCommand
Dim reader As SqlDataReader
connection.Open()
cmd = New SqlCommand(query, connection)
reader = cmd.ExecuteReader
While reader.Read
cbxType.Items.Add(reader.Item("Name"))
End While
connection.Close()
Note: You are saying 2 comboboxes but your code seemed to be loading all the items to a single combobox. If you really need 2 comboboxes then use 2 SqlCommand and Reader loops (actually it would be better if you simply have used Linq for this).
You should be a bit more specific on what columns you are pulling from the 2 tables. if they are similar, you could write a sql query to UNION ALL the fields with a simple control to identify which record came from which table.
Example of SQL command string:
"SELECT 'M' AS Ctl, MealName AS aName FROM dbo.Dishes " &
"UNION ALL " &
"SELECT 'D' AS Ctl, DessertName AS aName FROM dbo.Desserts"
As mentioned by many here already, it seems like you are referencing only 1 ControlBox to list the fields returned cbxType
below is the reader (adapted to 2 ComboBoxes):
While reader.Read
Select Case reader.Item("Ctl")
Case "M"
cbxMType.Items.Add(reader.Item("aName"))
Case "D"
cbxDType.Items.Add(reader.Item("aName"))
End Select
End While
Hope this helps
So I have a MS Access Database with 1 table (Records) and 2 fields in it ("RecordID" (Number), which is the primary key, and "LowRes" (OLE Object) which is a low Resolution image). There are about 100 records.
I/m trying to load the Access Table into a DataTable (ID_Table) in VB.net.
Code so far:
Dim cnString As String = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=SBS2257_ID.accdb;"
Dim theQuery As String = "SELECT [RecordID], [LowRes] FROM [Records];"
Using CN As New OleDbConnection(cnString)
Dim command As New OleDbCommand(theQuery, CN)
Using objDataAdapter = New OleDbDataAdapter(command)
Dim ID_Table As New DataTable
CN.Open()
Dim pictureData As Byte() = DirectCast(command.ExecuteScalar(), Byte())
Dim picture As Image = Nothing
Using stream As New IO.MemoryStream(pictureData)
picture = Image.FromStream(stream)
objDataAdapter.Fill(ID_Table)
End Using
End Using
End Using
However the "DirectCast" command fails when I tell it to look at more then 1 field in my SQL statement with a datatype mismatch (if I just do [LowRes] it does not throw a error). However, I get stuck again when trying to apply the result to the table via the objDataAdapter, it doesnt fill the table with anything? I also notice that "picture" only contains the first image in the database.
I could put this database query in a function using "WHERE RECORDID=..." and loop it manually building the table returning "picture" each time, but Id like to avoid running a function 100 times, esp one that access a database.
Is it possible to read the whole database that contains images and just load it directly into a Datatable in one big swoop?
EDIT: So I got this to work:
Dim strConnection As String = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=SBS2257_ID.accdb;"
Dim strSQL As String = "SELECT [RecordID], [LowRes] FROM [Records];"
Using objConnection = New OleDbConnection(strConnection)
Using objCommand = New OleDbCommand(strSQL, objConnection)
Using objDataAdapter = New OleDbDataAdapter(objCommand)
Dim objDataTable As New DataTable("IDs")
objDataAdapter.Fill(objDataTable)
Return objDataTable
End Using
End Using
End Using
how ever when I go to view row 0, col 1 which should be the first LowRes image via a .ToString Useing this code:
Private Sub PrintValues(ByVal table As DataTable)
For Each row As DataRow In table.Rows
For Each col As DataColumn In table.Columns
MsgBox(row(col).ToString())
Next col
Next row
End Sub
It just displays "System.Byte[]". It knows its a Byte datatype, but how do I display that in a picturebox?
The ExecuteScalar() executes the query, and returns the first column of the first row in the result set returned by the query.
as your query is
Dim theQuery As String = "SELECT [RecordID], [LowRes] FROM [Records];"
the first column is RecordID which is not a Byte().
you can change your query as following:
Dim theQuery As String = "SELECT [LowRes] FROM [Records];"
or you have to use other methods to get data from the database
Dim strSql As String = "SELECT [RecordID], [LowRes] FROM [Records]"
Dim dtb As New DataTable
Using cnn As New OleDbConnection(connectionString)
cnn.Open()
Using dad As New OleDbDataAdapter(strSql, cnn)
dad.Fill(dtb)
End Using
cnn.Close()
End Using
I want to know which is the best way to store database value in vb.net, For example, I've this code:
Dim conn As MySqlConnection = Connection() 'Return a connection obj
conn.Open()
Dim transaction = conn.BeginTransaction
Dim cmd = New MySqlCommand("SELECT * FROM tb ORDER BY ID")
Dim ResultSet = Cmd.ExecuteReader
If ResultSet.HasRows Then
Do While ResultSet.Read
'Here the value should be store
Loop
End if
How you can see I take all table from my database, now I want store each records in a structure that allow me to access it like the table. An array is good for do this? A list? Which is the best way?
There is no best way. You have different options. For example:
As an option you can use a DataTable
Also you can store values in a generic List(Of T).
If you prefer working with DataTable it will be more simple to use DataAdapter to fill the DataTable. This way you can also create your List(Of T) from your DataTable.
Example of Using DataDapter to fill DataTable
Dim Connection = "Connection String"
Dim Command = "SELECT * FROM Category"
Dim Adapter = New SqlDataAdapter(Command, Connection)
Dim Table = New DataTable()
Adapter.Fill(Table)
This way the DataTable will have columns with name of columns in your result set.
Also you can fill your data in a List(Of T) using the DataTable this way:
Dim ListOfCategory = Table.Rows.Cast(Of DataRow) _
.Select(Function(Row)
Return New Category With
{
.Id = Row.Field(Of Integer)("Id"),
.Name = Row.Field(Of String)("Name")
}
End Function).ToList()
Note
If can change the way you are writing your application, you can use Entity Framework as a good option to work with data.
I have 2 data sources from different source types, like:
Dim connSql As String = "Data Source=sql_src;Initial Catalog=my_db;Persist Security Info=True;User ID=usr;Password=pwd;"
Dim connOle As String = "Provider=IBMDA400;Data source=src;User Id=usr;Password=pwd"
dim qrySql as String = "Select uniqueID, name From tblSql"
dim qryOle as String = "Select name, ID From tblOle"
I place them into DataTables using functions like this (mostly for reference):
Public Shared Function sqlQryDT(qry As String, conn As String) As DataTable
Dim dt As New DataTable
Dim sqlconn As New SqlClient.SqlConnection(conn)
sqlconn.Open()
Dim adapter As New SqlClient.SqlDataAdapter(qry, sqlconn)
Try
adapter.Fill(dt)
Catch ex As Exception
Finally
sqlconn.Close()
End Try
Return dt
End Function
Public Shared Function oleQryDT(qry As String, conn As String) As DataTable
Dim dt As New DataTable
Dim cn As New OleDb.OleDbConnection(conn)
Dim cmd As New OleDb.OleDbCommand("", cn)
Dim da As New OleDb.OleDbDataAdapter(cmd)
cmd.CommandText = qry
Try
cn.Open()
da.Fill(dt)
Catch ex As Exception
Finally
cn.Close()
End Try
Return dt
End Function
Dim dtSql as DataTable = sqlQryDT(qrySql, connSQL)
Dim dtOle as DataTable = oleQryDT(qryOle , connOle)
My goal is to have a DataTable consisting of uniqueID,name,ID
(Edit) If I could do an SQL query it would look like SELECT * FROM dtSql JOIN dtOle ON dtSql.name = dtOle.name
I have tried using a DataRelation by placing the tables into a DataSet and adding a relationship on name, but since names may not be unique, this fails.
I have also tried using LINQ, but that always returns IEnumerable(System.Collections.Generic) and I can't find an easy way to place the contents into a DataTable, except by iterating through every item. And, the code is messy when there are a large number of columns.
I feel like there should be a way to do this without using a For Each loop
I looked at these question, but they didn't fully help me.
How to inner join two already filled DataTables in VB.NET
Merging 2 data tables in vb.net