How to programmatically connect to SQLite ?
lazarus / 16-Databases

----------------------------------------------------------------------
engine32 · 2022-11-15 01:35

Hello,

  I am working on an application with four worker threads that needs
access to the SQLite database. I read online that I should not use a
single connection established with visual component in the main thread
but use one connection per thread. I am looking for some advice of how
to establish the connection to the database and then read / write 
 to it from individual threads.

  Thank you.

----------------------------------------------------------------------
Leledumbo · 2022-11-15 01:45

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses  db,
sqldb, sqlite3conn;var  Conn: TSQLConnector;  Query: TSQLQuery;  F:
TField;begin  Conn := TSQLConnector.Create(nil);  with Conn do begin 
 ConnectorType := 'SQLite3';    HostName := ''; // unread by
underlying TSQLite3Connection    DatabaseName :=
'/path/to/sqlite/db/file.sqlite';    UserName := ''; // unread by
underlying TSQLite3Connection    Password := ''; // this is still
read, if you use the encrypted db feature    Transaction :=
TSQLTransaction.Create(Conn);  end;   Query := TSQLQuery.Create(nil); 
Query.DataBase := Conn;   Query.SQL.Text := 'select * from tables'; //
make your own query  Query.Open;  while not Query.EOF do begin    for
F in Query.Fields do begin      Write(F.FieldName,' = ');      if
F.IsNull then WriteLn('NULL') else WriteLn(F.Value);    end;   
WriteLn;    Query.Next;  end;  Query.Close;  Query.Free; 
Conn.Free;end.

----------------------------------------------------------------------
Zvoni · 2022-11-15 07:05

Quote from: Leledumbo on November 15, 2022, 02:45:54 amuses
  db, sqldb, mysql56conn;
*snipp*
  with Conn do begin
    ConnectorType := 'SQLite3';
*snipp*
?!?!???!??!??!
Especially for SQLite don't forget to set the proper OpenFlags, and,
IIRC, to set Journal_mode-Pragma to WAL

----------------------------------------------------------------------
Leledumbo · 2022-11-15 08:55

Quote from: Zvoni on November 15, 2022, 08:05:54 amQuote from:
Leledumbo on November 15, 2022, 02:45:54 amuses
  db, sqldb, mysql56conn;
*snipp*
  with Conn do begin
    ConnectorType := 'SQLite3';
*snipp*
?!?!???!??!??!
Especially for SQLite don't forget to set the proper OpenFlags, and,
IIRC, to set Journal_mode-Pragma to WAL
Oops, forgot to change that. My original example code was indeed to
connect with MySQL 5.6 or MariaDB 10.0 equivalent.