Do I need to use SqlConnection.Open() inside:
using (SqlConnection var = new SqlConnection())
{
//my operations
}
?
What happens if I don't dispose this connection by SqlConnection.Close() function?
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3 Answers
Yes, you need to Open your connection inside the using block.
If you don't explicitly Close() the connection, the end of the using block will do it for you as the using disposes of the connection. When a connection is disposed it is automatically closed.
Comments
The using statement is just syntactic sugar which ensures that Dispose gets called on the IDisposable instance no matter what, so in your case using (SqlConnection connection = new SqlConnection()) is roughly equivalent to (as per MSDN):
SqlConnection connection = new SqlConnection();
try
{
// Operations.
}
finally
{
if (connection != null)
{
connection.Dispose();
}
}
In the case of SqlConnection Dispose and Close calls are actually equivalent, so a call to Close would be redundant within a using (SqlConnection) block.
Calling Open, on the other hand, will still be necessary in many scenarios (before a call to ExecuteReader, ExecuteScalar, ExecuteNonQuery, for example). The using statement has no effect on whether or not you need to explicitly open the connection - only on whether or not you need to explicitly close it.
Comments
Provides a convenient syntax that ensures the correct use of IDisposable objects
using Implements IDisposable Internally
using(SqlConnection con=new SqlConnection("myCOnstr"))
{
con.open();
using(SqlCommand con=new SqlCommand("myCmd",con))
{
//......Insert/Update /Delete
}
}
