SQLite, code only, no TSQLite3Connection
lazarus / 16-Databases

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jbmckim · 2018-02-03 00:55

I like the DB connectors and I'll use the SQLite connector if need be
but I was wondering if there was a "code only" solution.  I'm starting
what will likely be a rather large project and I'd like to have my DB
access all run through one unit.  This unit will be a worker bee and
won't have a UI.  I've looked and maybe my Google skills aren't that
sharp but everything I find uses the connectors dropped on a UI.

Thanks.

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valdir.marcos · 2018-02-03 02:14

Take a look here:
[Solved]How can I create TSQLite3 components in a unit at run time.
http://forum.lazarus.freepascal.org/index.php/topic,30398.msg193409.ht
ml#msg193409

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GAN · 2018-02-03 02:27

I use this unit in my projects. I use ZeosLib but it will serve as a
guide.

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 unit
dbfunctions; {$mode objfpc}{$H+} interface uses    Classes, SysUtils,
db, ZConnection, ZDataset, FileUtil    ; function DB_Exists (sDBase,
sTable, sField, sValue: String) : Integer; implementation  function
DB_Exists (sDBase, sTable, sField, sValue: String) : Integer;    //-1
Database does not existvar                                           
                          // 0 Database not Found  ZConn:TZConnection;
                                                    // >0 Number of
records found  ZQry:TZQuery;  DSource:TDataSource; 
iRet:Integer=0;begin  if not(FileExists(sDBase)) then Exit(-1); 
ZConn:=TZConnection.Create(nil);  ZQry:=TZQuery.Create(nil); 
DSource:=TDataSource.Create(nil);  ZConn.Protocol:='sqlite-3'; 
ZConn.Database:=sDBase;  ZConn.Connect;  ZQry.Connection:=ZConn; 
DSource.DataSet:=ZQry;  DSource.Enabled:=True;  ZQry.SQL.Text:='SELECT
'+sField+' FROM '+sTable+' WHERE '+sField+'='+QuotedStr(sValue)+' ;'; 
ZQry.Open;  iRet:=ZQry.RecordCount;  ZQry.Close; 
DSource.Enabled:=False;  ZConn.Disconnect;  FreeAndNil(ZConn); 
FreeAndNil(ZQry);  FreeAndNil(DSource);  DB_Exists:=iRet;end; end.

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Thaddy · 2018-02-03 10:09

Quote from: valdir.marcos on February 03, 2018, 03:14:44 amTake a look
here:
[Solved]How can I create TSQLite3 components in a unit at run time.
http://forum.lazarus.freepascal.org/index.php/topic,30398.msg193409.ht
ml#msg193409

Indeed. Actually I never use the visual component, I always do it like
that.

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jbmckim · 2018-02-03 21:36

Thanks all,

Just to put things (mostly) all in one place:

You do need some things in "uses"

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,...;
Then this - I put this in the global vars for the unit:

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 var 
DBconnection: TSQLite3Connection; 
Then this:

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
DBconnection := TSQLite3Connection.Create(nil);  
Mostly putting this here so I can google it later to remind myself

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jbmckim · 2018-02-03 21:43

And here's a good example of how to use after things are defined:

http://wiki.freepascal.org/TSQLite3Connection