there's anyone can help me with my vb.codes? i'm new in vb.net and i want to know how to add data in mysql database using n-tier in vb.net. this is may current code in adding data:
Data Layer:
Public Function addData() As DataTable
Dim myCommand As String = "Insert Into tblItems VALUES (#Itemcode, #Itemname, #Itemdescription, #Itemtype, #Itempricing, #Itemonstock, #Itemprice, #Datemod)"
con.Open()
Dim sda As New MySqlDataAdapter(myCommand, con)
Dim dt As DataTable = New DataTable
sda.Fill(dt)
Return dt
End Function
sorry for my code. i really don't know how can i use that in BLL and PL. please help me. i really want to learn from all of you guys..
PS: sorry for my english i'm a 14 yr old and i want to learn programming. i did a research but i can't find what i'm really looking for. thanks in advance.
To insert a new record in a datatable you need to execute a command and provide the values to be sent to the database table.
You need something like this.
Public Function addData(itmCode as String, itmName as String.... omitted the other values) As Integer
Dim myCommand As String = "Insert Into tblItems VALUES " & _
"(#Itemcode, #Itemname, #Itemdescription, " & _
"#Itemtype, #Itempricing, #Itemonstock, #Itemprice, #Datemod)"
con.Open()
Dim cmd As New MySqlCommand(myCommand, con)
cmd.Parameters.AddWithValue("#ItemCode", itmCode)
cmd.Parameters.AddWithValue("#ItemName", itmName)
.... other parameters for the other values to insert will follow....
Dim rowInserted = cmd.ExecuteNonQuery()
return rowInserted
End Function
This requires that you pass to the function the values through a set of variables which values are added to the parameter collection of the command and finally execute the command.
The execution returns the number of records inserted/changed/deleted.
Notice also that your query doesn't specify a field list, so you need to pass the values to update every single field in the underlying datatable with the exact order.
Related
I am trying to find the max product ID and store the value in a local variable "MaxID" and return this value. I am trying to convert the result of the query into an Integer type but I am not able to do it. Below is the code:
Public Function GetMaxID(ByVal TableName As String, ByVal ID As String) As Integer
Dim MaxID As Integer
Dim sqlquery As SqlCommand
Dim field_name As String = ID
Dim con As SqlConnection
con = New SqlConnection()
con.ConnectionString = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename='D:\Docs Dump\Work\Srinath\SrinathDB.mdf';Integrated Security=True;Connect Timeout=30"
con.Open()
Try
sqlquery = New SqlCommand("SELECT MAX( #field ) FROM #table ", con)
sqlquery.Parameters.AddWithValue("#field", field_name)
sqlquery.Parameters.AddWithValue("#table", TableName)
MaxID = CInt(sqlquery.ToString)
con.Close()
Return MaxID
Catch ex As Exception
Return 0
Exit Function
con.Close()
End Try
End Function
End Class
MaxID = CInt(sqlquery.ExecuteScalar())
You also should know about SqlCommand.ExecuteReader(), SqlCommand.ExecuteNonQuery() (for inserts/updates/deletes), and SqlDataAdapter.Fill().
Where you'll still have a problem is you can't use a parameter value for the table name or column name. The Sql Server engine has a "compile" step, where it has to be able to work out an execution plan, including permissions/security, at the beginning of the query, but variable names like #table and #field aren't resolved until later. It's not what actually happens, but think of it as if you had string literals in those places; imagine trying to run this:
SELECT MAX('ID') FROM 'MyTable'
MAX('ID') will always return the string value ID, and not anything from an ID column in any rows. But the MyTable part is not the correct place for a string literal, and such a query wouldn't even compile.
I also see people here from time to time try to create functions like GetMaxId(), and it's almost always misguided in the first place. If the intended use for this function is the same as what I usually see, you're setting up a major race condition issue in your application (one that probably won't show up in any testing, too). Sql Server gives you features like identity columns, sequences, and the scope_identity() function. You should be using those in such a way that new IDs are resolved on the server as they are created, and only (and immediately) then returned to your application code.
But that issue aside, here's a better way to structure this function:
Public Class DB
Private conString As String = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename='D:\Docs Dump\Work\Srinath\SrinathDB.mdf';Integrated Security=True;Connect Timeout=30"
'You want a separate method per-table that already knows the table and column names
Public Function GetMyTableMaxID() As Integer
Dim sql As String = "SELECT MAX(ID) FROM MyTable"
Using con As New SqlConnection(conString), _
sqlQuery As New SqlCommand(sql, con)
'Parameters would go here.
'Do NOT use AddWithValue()! It creates performance issues.
' Instead, use an Add() overload where you provide specific type information.
'No exception handling at this level. The UI or business layers are more equipped to deal with them
con.Open()
Return CInt(sqlQuery.ExecuteScalar())
End Using
'No need to call con.Close()
'It was completely missed in the old code, but handled by the Using block here
End Function
End Class
I am a little new to using vb.net and SQL so I figured I would check with you guys to see if what I am doing makes sense, or if there is a better way. For the first step I need to read in all the rows from a couple of tables and store the data in the way the code needs to see it. First I get a count:
mysqlCommand = New SQLCommand("SELECT COUNT(*) From TableName")
Try
SQLConnection.Open()
count = myCommand.ExecuteScalar()
Catch ex As SqlException
Finally
SQLConnection.Close()
End Try
Next
Now I just want to iterate through the rows, but I am having a hard time with two parts, First, I cannot figure out the SELECT statement that will jet me grab a particular row of the table. I saw the example here, How to select the nth row in a SQL database table?. However, this was how to do it in SQL only, but I was not sure how well that would translate over to a vb.net call.
Second, in the above mycommand.ExecuteScalar() tell VB that we expect a number back from this. I believe the select statement will return a DataRow, but I do not know which Execute() statement tells the script to expect that.
Thank you in advance.
A simple approach is using a DataTable which you iterate row by row. You can use a DataAdapter to fill it. Use the Using-statement to dispose/close objects property that implement IDisposable like the connection:
Dim table = New DataTable
Using sqlConnection = New SqlConnection("ConnectionString")
Using da = New SqlDataAdapter("SELECT Column1, Column2, ColumnX FROM TableName ORDER By Column1", sqlConnection)
' you dont need to open/close the connection with a DataAdapter '
da.Fill(table)
End Using
End Using
Now you can iterate all rows with a loop:
For Each row As DataRow In table.Rows
Dim col1 As Int32 = row.Field(Of Int32)(0)
Dim col2 As String = row.Field(Of String)("Column1")
' ...'
Next
or use the table as DataSource for a databound control.
I understand that there are other posts such as this, however I cannot find one that will work for me and Im really at the end of my tether with this, I really dont know what to do.
I have a few tables with ID columns and name columns, that are connected by Link Tables through foreign keys etc. I'm trying to enter data into the database via a GUI and to do so I'm using insert statements into the 'regular' tables, then Select statements to get the autogen IDs from the regular table to then insert into the link tables.
The code below is what I've been trying to use to do this.
Imports System.Data.SqlClient
Public Class Test
Private cs As New SqlConnection(".....")
Private Sub btnInsertNext_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnInsertNext.Click
Dim ContID As Integer
Dim FName As Integer
cs.Open()
Using command As New SqlCommand("Select FamID From Family Where Name = '" & FName & " '", cs)
command.Parameters.AddWithValue("#FamID", ContID)
command.ExecuteNonQuery()
End Using
Using command As New SqlCommand("Select DocID From Doctors Where DocName LIKE'" & AddFam.Doctor & " '", cs)
command.Parameters.AddWithValue("#DocID", AddFam.Doctor) ''AddFam is another form I'm using to add a family member to a Doctor
command.ExecuteNonQuery()
End Using
cs.close()
I'm using:
VB 2010
SQL server management 2008 r2
I understand its a bit muddley but any help would be greatly appreciated, and I'm sorry if this has come up before.
It's not really clear what problem you actually have, i assume that you don't know how to retrieve newly generated IDs.
Here is an self-explanatory example on how to retrieve new identity values with ADO.NET:
Using con = New SqlConnection(connectionString)
Dim newID As Int32
Using insertCommand = New SqlCommand("INSERT INTO Test(Value)VALUES(#Value);SELECT CAST(scope_identity() AS int)", con)
insertCommand.Parameters.AddWithValue("#Value", "Value1")
con.Open()
newID = DirectCast(insertCommand.ExecuteScalar, Int32)
End Using
If newID <> 0 Then
Using updateCommand = New SqlCommand("UPDATE TEST SET Value='Value1.1' WHERE idTest=#idTest", con)
updateCommand.Parameters.AddWithValue("#idTest", newID)
If con.State <> ConnectionState.Open Then con.Open()
Dim updatedRecordCount = updateCommand.ExecuteNonQuery
End Using
End If
End Using
The 2 important parts are:
SELECT CAST(scope_identity() AS int)
which will return the new identity value
DirectCast(insertCommand.ExecuteScalar, Int32)
which will return the new Identity column value if a new row was inserted, 0 on failure.
Since you're mixing using parameters with string-concatenation: using parameters is very important because it will prevent SQL-Injection.
SCOPE_IDENITY
ExceuteScalar-Method
Commands and Parameters in ADO.NET
NO! Parameterise your queries like this.
command = New SqlCommand("Select FamID From Family Where Name = #Fname", cs)
command.Parameters.AddWithValue("#Fname", ContID)
FamID = command.ExecuteScalar()
And ideally, you should use Scope_Identity() to get the Identity from you insert statement
You can try with this code on two queries based on # symbol
...
Using command As New SqlCommand("Select FamID From Family Where Name = #FamID", cs)
command.Parameters.AddWithValue("#FamID", ContID)
...
Using command As New SqlCommand("Select DocID From Doctors Where DocName LIKE #DocID", cs)
command.Parameters.AddWithValue("#DocID", AddFam.Doctor)
...
I have a ms sql table PRODUCTS.
And it has three columns ID (int),NAME (nvarchar),TSTAMP (timestamp)
I want to get new inserted row's both id and timestamp (like multiple select scope_identity).
I can achieve that in sql as following:
INSERT INTO PRODUCTS (NAME)
OUTPUT inserted.ID,inserted.TSTAMP
VALUES ('Example Product')
But how can i read it in vb.net with sqlclient.sqlcommad on insertation? Which function of sqlcommand do i have to use and how? ExecuteReader maybe?
Using the ExecuteReader() method of SqlCommand would work the same as with SELECT.
OUTPUT clause works like a SELECT statement but its usage differs in
INSERT, UPDATE and DELETE commands
Here's a sample code. Try it.
Dim connString As String = "server=Test; database=Test;" + _
"uid=sa; pwd="
Dim conn As New SqlConnection(connString)
Dim cmdString As String = "INSERT INTO PRODUCTS (NAME) " + _
"OUTPUT inserted.ID,inserted.TSTAMP " + _
"VALUES ('Example Product')"
Dim cmd As New SqlCommand(cmdString, conn)
conn.Open()
Dim reader As SqlDataReader = cmd.ExecuteReader()
conn.Close()
Here're some links
Running The OUTPUT Clause From C#
Implementing the OUTPUT Clause in SQL Server 2008
I have a SQLClient.DataSet in VB.NET, and I want to insert the entire thing into a SQL Server table without having to do the following:
For Each dr as Datarow in MyDataset
Dim sc As New SqlCommand("INSERT INTO MyNewTable " & _
"VALUES (#column1, #column2)", MyDBConnection)
sc.Parameters.AddWithValue("#column1", dr.Item(0))
sc.Parameters.AddWithValue("#column2", dr.Item(1))
sc.ExecuteNonQuery()
Next
Since I've got close to a million rows (all pretty skinny, so it's not much space), I obviously don't want to run this loop and generate a million INSERT statements.
I know that one option is to use a linked server when I initially fetch the data, since it's coming from another SQL Server, and just have it to the INSERT from there. However, if I already have the data in my application, is there a more efficient way to bulk insert it? Can I somehow pass the DataTable as a parameter to SQL Server and have it sort it out and insert the rows?
try with SqlBulkCopy
With SQL Server 2008 you can use Table-Valued Parameters:
Dim sc As New SqlCommand(
"INSERT INTO MyNewTable (field1, field2,...)"&
"SELECT field1, field2,... FROM #MyTable;", MyDBConnection)
sc.Parameters.AddWithValue("#MyTable", MyDataset)
sc.ExecuteNonQuery()
Use the SqlDataAdapter's InsertCommand to define your Insert query. Then call the DataAdapter's Update Method with your dataset as a parameter to have it push the data.
Something like:
Dim DA As SqlDataAdapter = New SqlDataAdapter
Dim Parm As New SqlParameter
DA.InsertCommand = New SqlCommand("Insert Into tbl1(fld0, fld1, fld2) Values(#fld0, #fld1, #fld2)", conn)
Parm = DA.InsertCommand.Parameters.Add(New SqlParameter ("#fld0", NVarChar, 50, "fld0"))
Parm = sqlDA.InsertCommand.Parameters.Add(New SqlParameter ("#fld1", SqlDbType.NVarChar, 50, "fld1"))
Parm = sqlDA.InsertCommand.Parameters.Add(New SqlParameter ("#fld2", SqlDbType.NVarChar, 50, "fld2"))
DA.Update(dataset1, "tbl1")
You could call .WriteXML() on the DataSet and dump that into the database in one insert.
A way simplier way is to use a table adapter. Then you can use the Fill method to give a datatable as argument :
Dim oStronglyTypedTable As StronglyTypedDataTable = GetTable() 'A custom function that creates your table from wherever you want)
If Not oStronglyTypedTable Is Nothing Then
Using oAdapter As New StronglyTypedTableAdapter
Dim res As Integer = oAdapter.Update(oStronglyTypedTable)
MsgBox(res & " rows have been updated.")
End Using
End If
Do not forget to change your Database "Copy to Output Directory" property to "Do net copy" and set your connection string properly...