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Reading a little bit more, I knew triggers can be used to implement
foreign keys when Sqlite version does not allow this feature. This
is my attempt: begin transaction; create table annotation_master ( id integer primary key not null, entry datetime not null, cathegory integer not null, subject varchar(40) not null, description text not null ); create table annotation_cathegory ( id integer primary key not null, title varchar(30) not null ); create trigger fkcathegory_id before insert on annotation_master for each row begin select case when((select id from annotation_cathegory where id = new.cathegory) is null) then raise(ABORT, 'This cathegory does not exist') end; end; commit; And the Lua script: require('luasql.sqlite3') require('classlib') require('date') module('dbr', package.seeall) filename = 'calau.dbl' class.annotation() function annotation:__init() obj = self self.env = luasql.sqlite3() self.con = self.env:connect(filename) self.cur = self.con:execute('select sqlite_version()') end function annotation:quit() obj.cur:close() obj.con:close() obj.env:close() end function annotation:append(cathegory, subject, description) local err, msg = obj.con:execute(string.format("insert into annotation_master(entry, cathegory, subject, description) values(datetime('now'), %d, '%s', '%s')", cathegory, subject, description)) return err, msg end reg = annotation() err, msg = reg:append(3, 'Assunto 1', 'Descrição 1') print(msg) reg:quit() When I print msg, Lua says that a Sqlite error occurs or because a database is missing or because of a logical Sqlite error. The database is correctly referenced and printing the schema in database, I can see the trigger and all the structure shown before was created. As a logical error is a general message, I could not identify my error. This is the first time I use triggers, so it is not properly surprising if I understand something completely wrong. In Sqlite website, I knew trigger support was added in 2.5 version and regarding Luasql works with 3.3.17, I presume this strategy can be used. -------- Mensagem original --------
Yes, you are right. Using sqlite3.exe, I had created the database with
these commands:
sqlite3 test.dbl
sqlite> pragma foreign_keys = on;
sqlite> .read test.sql
sqlite> sqlite_version();
3.7.5
and after:
lua test.lua
3.3.17
I created the database with 3.7.5 version, but when running the called
version was 3.3.17. I placed sqlite3.exe and Sqlite3.dll in ./clibs and
I though it would be sufficient to update my version. However, if I
understood the version embedded in luasql is older and there is no
support for foreign keys.
In Lua script, I tried also:
cur = con:execute('pragma foreign_keys = on')
But this attempt to enable via code the foreign key for the section
doesn't result. Yes, the problem seems to be the old version of Sqlite
used by Luasql.
Is the conclusion that I can't use foreign keys with
Luasqlite.sqlite3()? If the answer is yes, the alternatives could be:
1. To manage relations among tables not in the database, but in the Lua
code. When the number of tables or the number of relations are few,
perhaps it would be the easier approach.
2. To change to another database more powerful, supporting foreign keys.
But in this case, I don't want a separated process like Mysql.
Regarding a database which can be distributed together with the program
without additional instalations and foreign keys support, is there
another option of database? Could I use Luasql or should use another Lua
module?
Em 13/03/2011 00:11, Bob Chapman escreveu:
> On Sat, Mar 12, 2011 at 6:20 PM, Luciano de Souza<luchyanus@gmail.com> wrote:
>> Hi all,
>>
>> I want to use foreign keys in Sqlite3. I am using the modules available in
>> Lua for Windows and I downloaded the DLL and the commandline tool for
>> Sqlite3.
>> Does someone has an idea why I can't use foreign keys?
>>
> Does your example work for the command line tool? If so, this might be
> the problem:
>
> Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio
>> require "luasql.sqlite3"
>> env = luasql.sqlite3()
>> con = env:connect("")
>> cur = con:execute("select sqlite_version()")
>> print(cur:fetch())
> 3.3.17<====
>
> [Run using the Lua for Windows package]
>
> --
>
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