how do we open an already existing database fmdb a

问题:

I am using fmdb but i am not knowing where to add the db file. I found this old answer that i think it doesn't fit for xcode 4.2 (since we dont have 'Resources' folder anymore).

I created a database in 'Lita', added the extension .sqlite and added the db file as follows :

then tried to use the following

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docsPath = [paths objectAtIndex:0];
NSString *path = [docsPath stringByAppendingPathComponent:@"db.sqlite"];
FMDatabase *database = [FMDatabase databaseWithPath:path];
[database open];
FMResultSet *results = [database executeQuery:@"select * from tbl"];
printf("hi");
while([results next]) {
    printf("hi2");
NSString *name = [results stringForColumn:@"clm1"];
NSString *text  = [results stringForColumn:@"clm2"];        
NSLog(@"test: %@ - %@",name, text);
}
printf("done");

i am getting the 'hi' 'done' but never 'hi2'...

anyone can help?

回答1:

You want to add the (compiled) database to the project as a resource, and then copy it into the documents folder of the app on first start-up.

Here is an example method that does the work, call it from the applicationDidFinishLaunching and use the resultant FMDatabase * for all you queries.

- (FMDatabase *)openDatabase
{
    NSFileManager *fm = [NSFileManager defaultManager];
    NSString *documents_dir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *db_path = [documents_dir stringByAppendingPathComponent:[NSString stringWithFormat:@"database.s3db"]];
    NSString *template_path = [[NSBundle mainBundle] pathForResource:@"template_db" ofType:@"s3db"];

    if (![fm fileExistsAtPath:db_path])
        [fm copyItemAtPath:template_path toPath:db_path error:nil];
    FMDatabase *db = [FMDatabase databaseWithPath:db_path];
    if (![db open])
        NSLog(@"Failed to open database!");
    return db;
}

回答2:

I am working with the same issues right now. But to answer your question: the documents folder is the folder that is to be used in the device.

Put the database in the the supporting files folder.

Here is what works for me:

//hide status bar for full screen view
[[UIApplication sharedApplication]setStatusBarHidden:YES          withAnimation:UIStatusBarAnimationNone];

//set reference to database here
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            NSString *documentDir = [documentPaths objectAtIndex:0];
            self.databasePath = [documentDir stringByAppendingPathComponent:@"RPRA.sqlite"];

    [self createAndCheckDatabase];

    // Override point for customization after application launch.
    return YES;
}

//method used to create database and check if it exists

-(void) createAndCheckDatabase
{
    BOOL success;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    success = [fileManager fileExistsAtPath:self.databasePath];

    if(success) return;

    //else move database into documents folder
    NSString *databasePathFromApp = [[[NSBundle mainBundle] resourcePath]
                                     stringByAppendingPathComponent:@"RPRA.db"];

    [fileManager copyItemAtPath:databasePathFromApp toPath:self.databasePath error:nil];
}

回答3:

- (void)ensureDBFile
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *dbFilePath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"retails.sqlite"]];

    NSLog(@"Database Filepath Delgate = %@", dbFilePath);

    NSFileManager *fileManager = [NSFileManager defaultManager];
    BOOL dbFileExists = [fileManager fileExistsAtPath:dbFilePath];

    if(!dbFileExists){
        //Copy the db file if it didn't exist
        NSString *bundledDbPath = [[NSBundle mainBundle] pathForResource:@"retails" ofType:@"sqlite"];

        if (bundledDbPath != nil) {
            BOOL copiedDbFile = [fileManager copyItemAtPath:bundledDbPath toPath:dbFilePath error:nil];
            if (!copiedDbFile) {
                NSLog(@"Error: Couldn't copy the db file from the bundle");
            }
        }
        else {
            NSLog(@"Error: Couldn't find the db file in the bundle");
        }
    }
    self.db = [FMDatabase databaseWithPath:dbFilePath];
    [self.db setShouldCacheStatements:NO];
    [self.db open];
    if([self.db hadError]) {
    NSLog(@"Database Error %d: %@", [self.db lastErrorCode], [self.db lastErrorMessage]);
    }
}