K
Kay
Hello,
I have created a dataadapter by specifying the select command and then used
the SqlCommandBuilder to automatically generate the Update, Delete and
Insert commands. I fill the dataset, close the DB connection, open the
connection again, manually change the database, and then update the dataset
and call the dataadapter update method, I was expecting it to raise a
dbconcurrrency error but none was raised. why is this as the help on the
Microsoft pages states
"The logic for generating commands automatically for UPDATE and DELETE
statements is based on optimistic concurrency. That is, records are not
locked for editing and can be modified by other users or processes at any
time. Because a record could have been modified after it was returned from
the SELECT statement, but before the UPDATE or DELETE statement is issued,
the automatically generated UPDATE or DELETE statement contains a WHERE
clause such that a row is only updated if it contains all original values
and has not been deleted from the data source. This is done to avoid new
data being overwritten. In cases where an automatically generated update
attempts to update a row that has been deleted or that does not contain the
original values found in the DataSet, the command will not affect any
records and a DBConcurrencyException will be thrown."
any help would be appreciated,
Kay.
My code is as follows:
Dim dataset As New DataSet
Dim connectString As String = "db connection string is in here"
Dim myConn As New SqlConnection(connectString)
Dim SqlSelectCommand As New SqlCommand("SELECT ID, Description FROM optFrame
WHERE (RoleAccessRevised = 1)", myConn)
Dim dataadapter As New SqlDataAdapter(SqlSelectCommand)
dataadapter.MissingSchemaAction = MissingSchemaAction.AddWithKey
Dim cmdBuilder As New SqlCommandBuilder(dataadapter)
myConn.Open()
dataadapter.Fill(dataset, "optFrame")
myConn.Close()
'NOTE: At this point I go to sql server DB and manually change the data in
the specified row, hoping it will cause concurrency
myConn.Open()
Dim rowToUpdate As DataRow =
dataset.Tables("optFrame").Rows.Find(TextBox13.Text) 'NOTE : the row
specified in textbox13 exists and is updated
rowToUpdate.Item("Description") = TextBox14.Text
Try
dataadapter.Update(dataset, "optFrame") 'Note: concurrency is not
caught here
Catch ex As DBConcurrencyException
Label28.Text = "concurrency error"
End Try
myConn.Close()
I have created a dataadapter by specifying the select command and then used
the SqlCommandBuilder to automatically generate the Update, Delete and
Insert commands. I fill the dataset, close the DB connection, open the
connection again, manually change the database, and then update the dataset
and call the dataadapter update method, I was expecting it to raise a
dbconcurrrency error but none was raised. why is this as the help on the
Microsoft pages states
"The logic for generating commands automatically for UPDATE and DELETE
statements is based on optimistic concurrency. That is, records are not
locked for editing and can be modified by other users or processes at any
time. Because a record could have been modified after it was returned from
the SELECT statement, but before the UPDATE or DELETE statement is issued,
the automatically generated UPDATE or DELETE statement contains a WHERE
clause such that a row is only updated if it contains all original values
and has not been deleted from the data source. This is done to avoid new
data being overwritten. In cases where an automatically generated update
attempts to update a row that has been deleted or that does not contain the
original values found in the DataSet, the command will not affect any
records and a DBConcurrencyException will be thrown."
any help would be appreciated,
Kay.
My code is as follows:
Dim dataset As New DataSet
Dim connectString As String = "db connection string is in here"
Dim myConn As New SqlConnection(connectString)
Dim SqlSelectCommand As New SqlCommand("SELECT ID, Description FROM optFrame
WHERE (RoleAccessRevised = 1)", myConn)
Dim dataadapter As New SqlDataAdapter(SqlSelectCommand)
dataadapter.MissingSchemaAction = MissingSchemaAction.AddWithKey
Dim cmdBuilder As New SqlCommandBuilder(dataadapter)
myConn.Open()
dataadapter.Fill(dataset, "optFrame")
myConn.Close()
'NOTE: At this point I go to sql server DB and manually change the data in
the specified row, hoping it will cause concurrency
myConn.Open()
Dim rowToUpdate As DataRow =
dataset.Tables("optFrame").Rows.Find(TextBox13.Text) 'NOTE : the row
specified in textbox13 exists and is updated
rowToUpdate.Item("Description") = TextBox14.Text
Try
dataadapter.Update(dataset, "optFrame") 'Note: concurrency is not
caught here
Catch ex As DBConcurrencyException
Label28.Text = "concurrency error"
End Try
myConn.Close()
