我正在使用本教程在我的项目中实现 FMDB。但是我的代码没有返回任何值。这是检索值的代码。
-(NSMutableArray *) getCustomers
{
NSMutableArray *customers = [[NSMutableArray alloc] init];
FMDatabase *db = [FMDatabase databaseWithPath:[Utility getDatabasePath]];
[db open];
FMResultSet *results = [db executeQuery:@"SELECT * FROM customers"];
NSLog(@"results %i,%@,%@",[results intForColumn:@"id"],[results stringForColumn:@"firstname"],[results stringForColumn:@"lastname"]);
while([results next])
{
Customer *customer = [[Customer alloc] init];
customer.customerId = [results intForColumn:@"id"];
customer.firstName = [results stringForColumn:@"firstname"];
customer.lastName = [results stringForColumn:@"lastname"];
[customers addObject:customer];
}
[db close];
return customers;
}
当我在文档目录中检查 db 而不是 db 时，这里是日志
CRUD[47363:f803] db /Users/pingdanehog/Library/Application Support/iPhone Simulator/5.1/Applications/D9F19E7D-A232-4C4A-8218-58BC136053A7/Documents/Customers.db
这是我的数据库
它包含数据
但是我的结果值始终为空，请帮助之前运行过此代码，但是当我为该项目创建具有相同名称的新数据库时，它已经停止了。
这是结果的值。
results 0,(null),(null)
我已经在 appdelegate 文件中初始化了我的数据库
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
databaseName = @"Customers.db";
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentDir = [documentPaths objectAtIndex:0];
databasePath = [documentDir stringByAppendingPathComponent:databaseName];
[self createAndCheckDatabase];
// Override point for customization after application launch.
self.viewController = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil];
self.window.rootViewController = self.viewController;
[self.window makeKeyAndVisible];
return YES;
}
-(void) createAndCheckDatabase
{
BOOL success;
NSFileManager *fileManager = [NSFileManager defaultManager];
success = [fileManager fileExistsAtPath:databasePath];
if(success) return;
NSString *databasePathFromApp = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:databaseName];
[fileManager copyItemAtPath:databasePathFromApp toPath:databasePath error:nil];
}