forlano Messages: 1207 Registered: March 2006 Location: Italy
Senior Contributor
Hello,
I have a program that stores data on a local Sqlite3 db. Moreover it needs to connect to an online MySql db.
Can this scenario be managed? In case of affermative answer how to do it? It is convenient to have one .sch file or two?...
After trying several possibilities, to avoid error from CLANG (many duplicate and redefinition), I found a solution that is accepeted by CLANG. I am using a single .SCH file with the definition of the two dbs. In a .h file I have
The code related the sqlite3 db works but I have not yet connected the online MySql db. Still remain the doubts about what I am doing and if I must wait some drawback.
I wrote the following on github: https://github.com/slashmais/dbsqlite3
that I use for all my data, maybe you find something useful. This works
very well for me for a while now.
Sorry for the lack of description in readme, I still need to make
time & energy to tidy-up all these projects
forlano Messages: 1207 Registered: March 2006 Location: Italy
Senior Contributor
slashupp wrote on Sat, 09 May 2020 12:13
Hi Luigi
I wrote the following on github: https://github.com/slashmais/dbsqlite3
that I use for all my data, maybe you find something useful. This works
very well for me for a while now.
hth
Thank you for the reply.
I saw you did something interesting for sqlite3. I'll use something in future.
My problem now is different. I am working with two db simultaneously: sqlite3 and mysql. Each of them has its own .sch file. The problem is how to declare and use them without mix up the code.
WRT to Session, things get complicated here as you cannot obviously use global session (the one assigned with SQL = statement) for both databases.
This is no showstopper - Sql instances have constructor form with SqlSession as parameter while default Sql constructors are using global session.
Usually one DB is "dominant" for the application. In that case, it makes sense to assign global session for dominant database connection and use constructor with parameter for secondary one.
Now for the schema issue. Obviously, you need two schema files and import each one with its dialect, also duplicate all other details you need.
Simply #undef SCHEMADIALECT after the include and define a new value for it.
I will try to make a reference example for this...
forlano Messages: 1207 Registered: March 2006 Location: Italy
Senior Contributor
mirek wrote on Mon, 11 May 2020 10:21
I think that there are 2 separate issues:
- Session
and
- Schema
WRT to Session, things get complicated here as you cannot obviously use global session (the one assigned with SQL = statement) for both databases.
This is no showstopper - Sql instances have constructor form with SqlSession as parameter while default Sql constructors are using global session.
Usually one DB is "dominant" for the application. In that case, it makes sense to assign global session for dominant database connection and use constructor with parameter for secondary one.
Now for the schema issue. Obviously, you need two schema files and import each one with its dialect, also duplicate all other details you need.
Simply #undef SCHEMADIALECT after the include and define a new value for it.
I will try to make a reference example for this...
Mirek
Thanks for the reply.
I do not use SQL, so the I have no problem with sessions. I can use both, but currently with the same .SCH. Moreover when I create a new db of course appear tables not wanted belonging to the other db.
My problems is how to deal with two schema.
I have just tried to duplicate the code
#define SCHEMADIALECT <plugin/sqlite3/Sqlite3Schema.h>
#define MODEL <OrionVR/db.sch>
#include <Sql/sch_header.h>
#undef SCHEMADIALECT
#undef MODEL
#define SCHEMADIALECT <MySql/MySqlSchema.h>
#define MODEL <OrionVR/db2.sch>
#include <Sql/sch_header.h>
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