Question

I’m trying to build a database using 21 tables each bind with constraints. I have implemented the database in PHPmyAdmin and then download the structure script to import in my Android SQLite database.

But I would like to know what are the good practices in building relational databases with many tables in Android, and how to create them.

currently I have a class implementing SQLiteOpenHelper:

public class SqlSig extends SQLiteOpenHelper {

@Override
public void onCreate(SQLiteDatabase db) {
    for(int i = 0; i != ConfigBDD.requetes.length; i++){
        db.execSQL(ConfigBDD.requetes[i]);
    }
}
}

ConfigBDD.requetes[i] fetch a string array containing tables creation requests and constraints requests. This code doesn’t work at all, and logCat show an error with the PRIMARY KEY instruction:

 05-29 15:13:51.992: E/Database(8187): Failure 1 (near "KEY": syntax error) on 0x15c4b8
 when preparing 'CREATE TABLE IF NOT EXISTS `arret` ( `id` int(11) NOT NULL , `id_externe`
 varchar(10) DEFAULT NULL, `id_pid` int(11) NOT NULL, `nom` varchar(50) NOT NULL,
 `description` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`), KEY `id_pid` (`id_pid`) )
 DEFAULT CHARSET=utf8 =1 ;'.

I am pretty sure there are other ways to create this database but did not found any explanations about multi tables Android SQLite database creation…

Answer 1

Your:

CREATE TABLE IF NOT EXISTS `arret` ( 
  `id` int(11) NOT NULL , 
  `id_externe` varchar(10) DEFAULT NULL, 
  `id_pid` int(11) NOT NULL, 
  `nom` varchar(50) NOT NULL,
  `description` varchar(255) DEFAULT NULL, 
   PRIMARY KEY (`id`), 
   KEY `id_pid` (`id_pid`))
DEFAULT CHARSET=utf8 =1 ;

should probably look something like this if you want it to work in SQLite.

CREATE TABLE IF NOT EXISTS arret ( 
  id INTEGER PRIMARY KEY NOT NULL , 
  id_externe TEXT DEFAULT NULL,
  id_pid INTEGER NOT NULL,
  nom TEXT NOT NULL,
  description TEXT
);

followed by a CREATE INDEX for your id_pid which is what KEY implies in MySQL.