Call Open method to open connection to a DBMS, using specified connection string and optional user name and password. The method is shortcut to filling of Params property and setting Connected to True. 

AConnectionString string value may be one of two forms:

• it is a ';' separated list of the <name>=<value> connection definition parameter pairs. If connection string contains User_Name and/or Password parameters and AUserName and/or APassword arguments are specified, then they will override corresponding parameters in connection string.
• it is a connection definition name.

procedure Open(const AConnectionString: String; const AUserName: String; const APassword: String); overload;

Params, ConnectionDefName, DriverName, Connected, Open(String), Open(String, String)