Fill () method and conn. open ()

When the fill () method is called, if the connection is not opened, fill () is automatically opened and closed after the data is filled.

If a connection is enabled when the fill () method is called, fill () will use this connection, but won't close it after it uesd it!

Although datasets are completely independent from databases and connections, using datasets does not mean that they are disconnected from databases.

You can use a dataset to run it when it is disconnected, but do not open the L connection before filling it in (or close it if it is enabled first .). the dataset does not indicate that the connection is being disconnected or opened!

It should be in the finally {} conn. Close (); because it will not make an error when it is called when it is closed!