I have a VB.net script that needs to put information into a table in the database. The catch is that it is based off of an item Id, so when I am updating I cannot just insert the row would like to update the row if it is already there. For this I need to use the Update command like so:
mysqlCommand = New SQLCommand(UPDATE tableName Colum2=Newvalue ... Where Column1=ItemId)
However I am wondering if there is anyway to tell wether or not a line was updated when I run
mysqlcommand.ExecuteNonQuery()
so that I do not need to check before I run this command and switch between this update command and a INSERT INTO command
I agree with #Neolisk, but a slight improvement could be to use the following:
Dim recordsAffected As Integer = mysqlcommand.ExecuteNonQuery()
If recordsAffected > 0 Then 'it worked
or this:
Dim recordsAffected As Integer = mysqlcommand.ExecuteNonQuery()
If recordsAffected >= 1 Then 'it worked
#Neolisk's code will work great as long as Column1 is a unique identifier. Otherwise you may be updating more than one row. The "greater than"/"greater than or equal to" operator will catch the scenario where you are updating more than one row.
From documentation of SqlCommand.ExecuteNonQuery # MSDN:
Executes a Transact-SQL statement against the connection and returns the number of rows affected.
So you can write like this:
Dim recordsAffected As Integer = mysqlcommand.ExecuteNonQuery()
If recordsAffected = 1 Then 'it worked
EDIT: Regarding #macoms01 answer, my original intention was to have something like this:
Select Case recordsAffected
Case 0: 'it did not work
Case 1: 'it worked
Case Else: Throw New BadDataException
End Select
You can never be sure that unique constraints are set on the DB - expect bad data.
But then I thought it would probably be too complicated for its purpose.
Related
I'm currently using the following VB code to make a query against an Access Database, I would like to know is it possible to obtain what the SELECT statement that is being run and send that output to the console.
Dim QuestionConnectionQuery = New OleDb.OleDbCommand("SELECT Questions.QuestionID FROM Questions WHERE Questions.QuestionDifficulty=[X] AND ( Questions.LastDateRevealed Is Null OR Questions.LastDateRevealed < DateAdd('d',-2,Date() ) AND Questions.LastUsedKey NOT LIKE ""[Y]"" );", QuestionConnection)
QuestionConnectionQuery.Parameters.AddWithValue("X", questionDifficulty.ToString)
QuestionConnectionQuery.Parameters.AddWithValue("Y", strDatabaseKey)
Right now when I try to use: Console.WriteLine("Query: " & QuestionConnectionQuery.ToString)
I only get this:
Loop Question #1
Query: System.Data.OleDb.OleDbCommand
The short version comes down to this:
QuestionConnectionQuery.ToString
The QuestionConnectionQuery object is much more than just the text of your command. It's also the parameters, execution type, a timeout, and a number of other things. If you want the command text, ask for it:
QuestionConnectionQuery.CommandText
But that's only the first issue here.
Right now, your parameters are not defined correctly, so this query will never succeed. OleDb uses ? as the parameter placeholder. Then the order in which you add the parameters to the collection has to match the order in which the placeholder shows in the query. The code in your question just has X and Y directly for parameter placeholders. You want to do this:
Dim QuestionConnectionQuery AS New OleDb.OleDbCommand("SELECT Questions.QuestionID FROM Questions WHERE Questions.QuestionDifficulty= ? AND ( Questions.LastDateRevealed Is Null OR Questions.LastDateRevealed < DateAdd('d',-2, Date() ) AND Questions.LastUsedKey NOT LIKE ? );", QuestionConnection)
QuestionConnectionQuery.Parameters.Add("?", OleDbType.Integer).Value = questionDifficulty
QuestionConnectionQuery.Parameters.Add("?", OleDbType.VarChar, 20).Value = strDatabaseKey
I had to guess at the type and lengths of your parameters. Adjust that to match the actual types and lengths of the columns in your database.
Once you have made these fixes, this next thing to understand is that the completed query never exists. The whole point of parameterized queries is parameter data is never substituted directly into the sql command text, not even by the database engine. This keeps user data separated from the command and prevents any possibility of sql injection attacks.
While I'm here, you may also want to examine the WHERE conditions in your query. The WHERE clause currently looks like this:
WHERE A AND ( B OR C AND D )
Whenever you see an AND next to an OR like that, within the same parenthetical section, I have to stop and ask if that's what is really intended, or whether you should instead close the parentheses before the final AND condition:
WHERE A AND (B OR C) AND D
This will fetch the command text and swap in the parameter values. It isnt necessarily valid SQL, the NET Provider objects haven't escaped things yet, but you can see what the values are and what the order is for debugging:
Function GetFullCommandSQL(cmd As Data.Common.DbCommand) As String
Dim sql = cmd.CommandText
For Each p As Data.Common.DbParameter In cmd.Parameters
If sql.Contains(p.ParameterName) AndAlso p.Value IsNot Nothing Then
If p.Value.GetType Is GetType(String) Then
sql = sql.Replace(p.ParameterName,
String.Format("'{0}'", p.Value.ToString))
Else
sql = sql.Replace(p.ParameterName, p.Value.ToString)
End If
End If
Next
Return sql
End Function
Given the following SQL:
Dim sql = "INSERT INTO Demo (`Name`, StartDate, HP, Active) VALUES (#name, #start, #hp, #act)"
After parameters are supplied, you can get back this:
INSERT INTO Demo (`Name`, StartDate, HP, Active) VALUES ('johnny', 2/11/2010 12:00:00 AM, 6, True)
It would need to be modified to work with OleDB '?' type parameter placeholders. But it will work if the DbCommand object was created by an OleDBCOmmandBuilder, since it uses "#pN" internally.
To get or set the text of the command that will be run, use the CommandText property.
To print the results, you need to actually execute the query. Call its ExecuteReader method to get an OleDbDataReader. You can use that to iterate over the rows.
Dim reader = QuestionConnectionQuery.ExecuteReader()
While reader.Read
Console.WriteLine(reader.GetValue(0))
End While
reader.Close()
If you know the data type of the column(s) ahead of time, you can use the type-specific methods like GetInt32. If you have multiple columns, change the 0 in this example to the zero-based index of the column you want.
I need to update some code and as part of this I need to insert a row into a table and obtain the id (primary key) of the row just entered.
Have researched this and I believe I should be using RETURNING INTO and Oracle Parameters. I have used parameters in the past successfully to Insert values.
I have an INSERT statement that runs perfectly from VB.NET, but as soon as I add the text "" RETURNING id INTO :myId" I get ORA-00933 Command Not Properly Ended.
Here is a version of the code.
sql = "INSERT ... RETURNING id INTO :myId"
Connect()
Dim intRecsAffected As Integer = 0
Dim comm As OracleCommand = New OracleCommand(sql, _conn)
Dim param As OracleParameter
param = New OracleParameter()
param.ParameterName = ":myId"
param.OracleDbType = OracleDbType.Int32
param.Direction = ParameterDirection.Output ' Tried ReturnValue
comm.Parameters.Add(param)
intRecsAffected = comm.ExecuteNonQuery()
id = comm.Parameters(":myId").Value
Disconnect()
Any ideas?
I believe that your syntax is incorrect:
sql = "INSERT ... RETURNING id INTO myId"
Example below:
https://oracle-base.com/articles/misc/dml-returning-into-clause
Actually, realised what was going on. I cut my full SQL as it's quite long and there's some sensitive stuff in there.
The INSERT was using a SELECT rather than VALUES to get the values for the fields. That won't work - I am guessing because an INSERT with SELECT can add multiple rows even though in this case it won't.
Have re-written the SQL to use VALUES and the VB.Net code works fine.
Thanks to all who replied.
I have a situation where I want to Insert into access DB table from MS SQL table.
Same columns and everything.
I have both data sets and both table adapter. I can do what ever I want inside each dataset - any manipulation but I cannot insert from one table to another.
I tried creating an Insert query for destination tableadapter but I cannot get the from working. Tried linking, nothing works.
Searched for days, simply cannot find it.
Thank you for your answer. Can you help me on my example. I'm having trouble setting this up. This is what i got:
Dim myToTableTableAdapter As FirstDataSetTableAdapters.ToTableTableAdapter
myToTableTableAdapter = New FirstDataSetTableAdapters.ToTableTableAdapter()
Dim myFromTableTableAdapter As SecondDataSetTableAdapters.FromTableTableAdapter
myFromTableTableAdapter = New SecondDataSetTableAdapters.FromTableTableAdapter()
myFromTableTableAdapter = myToTableTableAdapter.Clone
'but it doesnt work from here`
What I wanted to do is:
For each drfrom As DataRow In myFromTableTableAdapter.GetData
myToTableTableAdapter.InsertInto(drfrom.item(column01), drfrom.item(column02), drfrom.item(andSoOn))
Next
But it seem to me that this would take so much longer then a "Insert Into From Select" script.
You cannot insert a row from one table into another table, but there are a couple of ways to do what you want. One way (a little verbose) is this:
' sets it up with same schema but empty rows
mOutTable = inTable.Clone
' Now insert the rows:
For Each rowIn In inTable.Rows
r = mOutTable.NewRow()
For Each col In inTable.Columns
r(col.ColumnName) = rowIn(col.ColumnName)
Next
mOutTable.Rows.Add(r)
Next
mOutTable.AcceptChanges
A second way, which is more concise, is this:
outTable = inTable.Clone
For Each inRow As DataRow In inTable.Rows
outTable.LoadDataRow(inRow.ItemArray, False)
End If
outTable.AcceptChanges
Note that both inTable and outTable are ADO.NET DataTable objects. You cannot implement my suggestion on the DataAdapter objects. You must use the DataTable objects. Each DataTable can be associated with a DataAdapter in the standard fashion for ADO.NET:
Dim t as New DataTable()
a.Fill(t);
where a is the ADO.NET DataAdapter. I hope this helps!
Jim
I want to link the result of a query to a Textbox but I get this error: here is my code:
Dim rst As DAO.Recordset
Set rst = CurrentDb.OpenRecordset("SELECT XValue, YValue,Wert FROM tb_DCM_Daten WHERE (FzgID=" & Forms!frm_fahrzeug!ID & " AND Name='" & List2.Value & "')")
Text10.Text = rst!XValue //error in this line
It should be return c.a 20 record
Why do I get this error and how can I solve it?
One possible reason for the error is that Name is a reserved word in Access, so you should use
... & " AND [Name]='" & ...
You could also test for rst.EOF before trying to use rst!XValue. That is, to verify whether or not your query is returning at least one row you can add the code
If rst.EOF Then
MsgBox "The Recordset is empty."
End If
immediately after the .OpenRecordset call. If the Recordset is empty, then you'll need to verify your SQL statement as described by #GregHNZ in his comment above.
Usually, I would do this. Create a new query in Access , switch to SQL View , Paste my code there and go to Design >> Run.
SELECT XValue, YValue,Wert FROM [tb_DCM_Daten] WHERE [FzgID]=12 AND [Name]='ABC';
if your query syntax is correct you should see the result otherwise error mssg will tell where you are wrong. I used to debug a much more complicated query than yours and this is the way that I've done.
If there is still error, maybe you should try
Dim sql as String
sql = "SELECT...."
Set rst = CurrentDb.OpenRecordset(sql)
Another possible reason might be your table name. I just wonder what is your table name exactly ? if your table contains white space you should make it like this [DCM Daten].
One more thing I like to add that may cause this, is your returning a sets of resultset that has "Reserved word" fields, for example:
Your "Customers" table has field name like the following:
Custnum | Date | Custname
we know that Date field is a reserved word for most database
so when you get the records using
SELECT * FROM Customers
this will possible return "No Current Record", so instead selecting all fields for that table, just minimize your field selection like this:
SELECT custnum, custname FROM Customers
After trying the solutions above to no avail, I found another solution: Yes/No fields in Access tables cannot be Null (See allenbrowne.com/bug-14)
Although my situation was slightly different in that I only got the "No current record." error when running my query using GROUPBY, my query worked after temporary eliminating the Yes/No field.
However, my Yes/No field surprisingly did not contain any Nulls. But, troubleshooting led me to find an associated error that was indeed populating my query result with Null Yes/No values. Fixing that associated error eliminated the Null Yes/No values in my results, thus eliminating this error.
I got the same error in the following situation:
In my case the recordset returned one record including some fields with Null value.
Dim rst As DAO.Recordset
Set rst = CurrentDb.OpenRecordset("SELECT * FROM tbl WHERE (criteria)", dbOpenDynaset)
Textbox1 = rst!field1 'error in this line - Non-Null value
Textbox2 = rst!field2 'Null value
Textbox3 = rst!field1 'Null value
Viewing Locals when rst is opened and before asignments, shows the recordset as I expect it to be. The error is thrown when trying to a asign a value from this recordset.
What fixed this, is ensuring that all fields contained non-Null values.
Just posting this for future seekers.
I am encountering a strange problem when attempting to execute a DELETE query agains a SQL Server table using VB.NET, SQL Command, and Parameters.
I have the following code:
Try
sqlCommand.Transaction = transaction1
sqlCommand.Connection = conn
sqlCommand.CommandText = sqlQuery
sqlCommand.Parameters.Add("#userID", SqlDbType.Int).Value = Convert.ToInt32(userID)
sqlCommand.Parameters.Add("#groupID", SqlDbType.Int).Value = Convert.ToInt32(groupID)
''#Delete the user from the group.
MessageBox.Show("User: " + Convert.ToString(userID) + " Group: " + Convert.ToString(groupID))
MessageBox.Show("Param, UserID: " + sqlCommand.Parameters.Item(0).Value.ToString)
MessageBox.Show("Param, GroupID: " + sqlCommand.Parameters.Item(1).Value.ToString)
return_deleteUser = sqlCommand.ExecuteNonQuery()
Catch ex As Exception
transaction1.Rollback()
Dim hr As Integer = Marshal.GetHRForException(ex)
MsgBox("Removal of user from group has failed: " + ex.Message() & hr)
End Try
Which executes the following SQL Query:
Dim sqlQuery As String = "DELETE FROM MHGROUP.GROUPMEMS WHERE USERNUM =#userID AND GROUPNUM =#groupID"
My problem is that when the code executes, there is no error reported at all. I have ran SQL Profiler and the query doesn't appear in the trace list. The three messageboxes that I have added all return the correct values, and if I was to execute the SQL query against the table with the values the query succeeds. Both the userID and groupID are 3-digit integers.
Can anyone suggest why the code is not working as intended, or any further debugging that I can use to step through the code? Ideally I would love to see the completed SQL query with the parameters completed, but I haven't found out how to do this.
EDIT:
I have the following later in the code to check if the execute's all processed successfully:
If return_insertEvent > 0 And return_updateUser > 0 And return_nextSID > 0 And return_deleteUser > 0 Then
MessageBox.Show("Success")
return_removeADGroup = RemoveUserFromGroup(userID, groupName)
MessageBox.Show("Remove FS User from AD Group: " + return_removeADGroup)
transaction1.Commit()
transaction2.Commit()
transaction3.Commit()
transaction4.Commit()
returnResult = 1
Else
transaction1.Rollback()
transaction2.Rollback()
transaction3.Rollback()
transaction4.Rollback()
returnResult = 0
End If
If you require any further information please don't hesitate in contacting me.
You are missing a Transaction.Commit
Update in respone to additional info added to question:
Why do you have 4 transactions? Since their commit and rollbacks are all executed together, you only need one transaction. I suggest you use a TransactionScope
You can assign the current transaction to ADO.NET Command objects:
ADO.NET and System.Transactions
Transaction Processing in ADO.NET 2.0
I might guess that your calling proc has the values of userid and groupid backwards. If the DELETE doesn't find a matching record, it will complete successfully, but not do anything. I suggest wrapping your delete up in a stored procedure. Then you can add code to test if the parameter values are getting through correctly.
Create Procedure UserDelete
#userid int, #groupID int
As
BEGIN
Select #userid as UID, #groupID as GID INTO TESTTABLE;
DELETE FROM MHGROUP.GROUPMEMS WHERE USERNUM =#userID AND GROUPNUM =#groupID;
END
Run your code then go check the contents of TESTTABLE.
FWIW: I don't like trying to get the whole parameter declaration in one line. Too much going on for me. I like this...
Dim pUID as New Parameter("#userid", SqlDbType.Int)
pUID.Value = userid
cmd.Parameters.Add(pUID)
After some time debugging and sql tracing, I have found out that the stupid application that the DB belongs to treats the group members differently, the groups reside in a administration database, but the users membership to the group resides in another database.
Thank you to everyone above who provided there time and thoughts in assisting with the code. I have changed the code as recomended to use only two transactions and two connections (1 for the admin and sub-database). The code is much nicer now and is that bit easier to read.
Thanks again,
Matt