how to create a sqlite

how to create a sqli开发者_Go百科te file when the application starts (didFinishLaunchingWithOptions) the test if it already or not exsist otherwise create the file sqlite

Like this... the sqlPath variable is the path to the pre-made sql database on your ressource

- (void) checkAndCreateSQL
{
    if (![[NSFileManager defaultManager] fileExistsAtPath:[documentPath stringByAppendingString:@"/database.sql"]]) {
        [[NSFileManager defaultManager] createFileAtPath:[documentPath stringByAppendingString:@"/database.sql"] 
                                                contents:[NSData dataWithContentsOfFile:sqlPath]
                                              attributes:nil];
    }
}

EDIT 1:

You can create the database on your mac using this command line :

sqlite3 database.sql < DATABASE_CREATION.txt

in the DATABASE_CREATION.txt something like this :

CREATE TABLE IF NOT EXISTS `group` (
  `id` integer PRIMARY KEY,
  `name` text,
  `position` integer
);

Then put directly the database.sql file into your project resource. (like an image)

You'd probably want to use the default Core Data libraries instead of manually creating and handling a single sqlite file. Please check the official Apple Core Data Programming Guide. It will automatically handle the creation and update of the inner database in the app.

sqlite3 *reference2Database() {
if (_database == nil) {
    // First, test for existence.
    NSError *error;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"my.sqlite"];

    if ([fileManager fileExistsAtPath:writableDBPath] == NO) {
        // Database file doesnt exists. Copy the database at writable path (documents directory).
        NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"my.sqlite"];

        [fileManager removeItemAtPath:writableDBPath error:nil];

        BOOL databaseCopied = [fileManager copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error];
        if (!databaseCopied) {
            // Handle the error...
        }
    }else {
        // Open the database. The database was prepared outside the application.
        if (sqlite3_open([writableDBPath UTF8String], &_database) != SQLITE_OK) {
            // Even though the open failed, call close to properly clean up resources.
            sqlite3_close(_database);
            _database = nil;
            // Additional error handling, as appropriate...
        }
    }
}
return _database;
}

// Sample usage.

-(void) someDatabaseFunction {
   sqlite3 *database = reference2Database();
   // Do something with "database"...
}

// Close the database. This should be called when the application terminates.

void closeDatabase() {
if (_database == nil) return;
// Close the database.
if (sqlite3_close(_database) != SQLITE_OK) {
    // Handle the error...
}
_database = nil;

}

NOTE: At the top of the file, you should have: static sqlite3 *_database = nil;

I use Matteo Bertozzi's SQLite Wrapper to create my sqlite database with the following code:

-(void)checkDatabase 
{
    if([[NSFileManager defaultManager] fileExistsAtPath:DBPATH] == NO)
    {
        sqlite = [[Sqlite alloc] init];

        if (![sqlite open:DBPATH]) return;

        [sqlite executeNonQuery:@"DROP TABLE yourtable"];
        [sqlite executeNonQuery:@"CREATE TABLE yourtable (record1 TEXT NOT NULL, 
                                                           record2 TEXT NOT NULL, 
                                                           record3 TEXT NOT NULL, 
                                                           record4 TEXT NOT NULL);"];

        NSArray *results = [sqlite executeQuery:@"SELECT * FROM yourtable;"];
        for (NSDictionary *dictionary in results) {

            for (NSString *key in [dictionary keyEnumerator])
                NSLog(@" - %@ %@", key, [dictionary objectForKey:key]);
        }

        [results release];
        [sqlite release];
    }
}