TDatabase¶
Base class for connecting a FreePascal application to an external Database engine.
Declaration¶
Source position: db.pas line 2288
type
TDatabase = class(TCustomConnection)
public
constructor Create;
destructor Destroy;
procedure CloseDataSets;
procedure CloseTransactions;
procedure StartTransaction;
procedure EndTransaction;
property TransactionCount: LongInt; {r}
property Transactions[Index : LongInt]: TDBTransaction; {r}
property Directory: string; {rw}
property IsSQLBased: Boolean; {r}
published
property Connected: Boolean; {rw}
property DatabaseName: string; {rw}
property KeepConnection: Boolean; {rw}
property Params: TStrings; {rw}
end;
Inheritance¶
Description¶
TDatabase is a component whose purpose is to provide a connection to an external database engine, not to provide the database itself. This class provides generic methods for attachment to databases and querying their contents; the details of the actual connection are handled by database-specific components (such as SQLDb for SQL-based databases, or DBA for DBASE/FoxPro style databases).
Like TDataset, TDatabase is an abstract class. It provides methods to keep track of datasets connected to the database, and to close these datasets when the connection to the database is closed. To this end, it introduces a Connected boolean property, which indicates whether a connection to the database is established or not. The actual logic to establish a connection to a database must be implemented by descendent classes.
Properties¶
| Member | Visibility | Description |
|---|---|---|
| Connected | published | Is the database connected. |
| DatabaseName | published | Database name or path. |
| Directory | public | Directory for the database. |
| IsSQLBased read only | public | Is the database SQL based. |
| KeepConnection | published | Should the connection be kept active. |
| Params | published | Connection parameters. |
| TransactionCount read only | public | Number of transaction components connected to this database. |
| Transactions read only | public | Indexed access to all transaction components connected to this database. |
Methods¶
| Member | Visibility | Description |
|---|---|---|
| CloseDataSets | public | Close all connected datasets. |
| CloseTransactions | public | End all transactions. |
| Create | public | Initialize a new TDatabase class instance. |
| Destroy | public | Remove a TDatabase instance from memory. |
| EndTransaction | public | End an active transaction. |
| StartTransaction | public | Start a new transaction. |