Executing scripts is accomplished through the ExecScript and Open methods of the TEDBScript component, or by setting the Active property to True. Before executing a script you must first specify the source database for the script. The source database is specified via the DatabaseName property of the TEDBScript component. The actual script is specified in the SQL property.

Setting the DatabaseName Property

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You may specify the DatabaseName property using two different methods:

1) The first method is to set the DatabaseName property of the TEDBScript component to the DatabaseName property of an existing TEDBDatabase component within the application. In this case the actual source database being used will come from the Database property. The following example shows how to use the DatabaseName property to point to an existing TEDBDatabase component for the source database:

begin
   with MyDatabase do
      begin
      DatabaseName:='AccountingDB';
      Database:='Accounting';
      Connected:=True;
      end;
   with MyScript do
      begin
      DatabaseName:='AccountingDB';
      SQL.LoadFromFile('c:\scripts\GetLedgerEntries.sql');
      Active:=True;
      end;
end;

Another useful feature is using the BeforeConnect event of the TEDBDatabase component to dynamically set the Database property before the TEDBDatabase component attempts to connect to the database. This is especially important when you have the Connected property for the TEDBDatabase component set to True at design-time during application development and wish to change the Database property before the connection is attempted when the application is run.

2) The second method is to enter the name of an existing database directly into the DatabaseName property. In this case a temporary database component will be automatically created, if needed, for the database specified and automatically destroyed when no longer needed. The following example shows how to use the DatabaseName property to point directly to the desired database without referring to a TEDBDatabase component:

begin
   with MySession do
      begin
      SessionName:='Remote';
      SessionType:=stRemote;
      RemoteAddress:='192.168.0.2';
      Active:=True;           
      end;
   with MyScript do
      begin
      SessionName:='Remote';
      DatabaseName:='Accounting';
      SQL.Clear;
      SQL.Add('SCRIPT ()');
      SQL.Add('BEGIN');
      SQL.Add('   EXECUTE IMMEDIATE ''BACKUP DATABASE Test ');
      SQL.Add('       AS TestBackup TO STORE "Backups" ');
      SQL.Add('       INCLUDE CATALOG'';');
      SQL.Add('END');
      ExecScript;
      end;
end;

Setting the SQL Property

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The script is specified via the SQL property of the TEDBScript component. You can use the ConvertSQL method to convert a script that consists of a series of SQL statements (INSERT, UPDATE, DELETE, or SELECT) separated by semicolons (;) into a proper ElevateDB script that can be executed by the TEDBScript component.

Preparing the script

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By default ElevateDB will automatically prepare a script before it is executed. However, you may also manually prepare a script using the TEDBScript Prepare method. Once a script has been prepared, the Prepared property will be True. Preparing a script compiles the script, opens all referenced tables, and prepares all internal structures for the execution of the script. You should only need to manually prepare a script when executing a script that requires parameters.

Executing the Script

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To execute the script you should call the TEDBScript ExecScript or Open methods, or you should set the Active property to True. Setting the Active property to True is the same as calling the Open method. The difference between using the ExecScript and Open methods is as follows:


The following example shows how to use the ExecScript method to execute a script:

begin
   with MyDatabase do
      begin
      DatabaseName:='AccountingDB';
      Database:='Accounting';
      Connected:=True;
      end;
   with MyScript do
      begin
      DatabaseName:='AccountingDB';
      SQL.LoadFromFile('UpdateLedgerEntries.SQL');
      Prepare;
      ParamByName('AccountNo').AsString:='00100';
      ExecScript;
      end;
end;

Tracking the Progress of a Script

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To take care of tracking the progress of the script execution, we have provided the TEDBScript OnProgress event. This event will only be fired if the script contains manual progress update calls specifically included by the script creator.