用SQLite管理数据库

http://www.yifeiyang.net/iphone-developer-advanced-9-management-database-using-sqlite/ iPhone开发进阶（9）--- 用SQLite管理数据库 今天我们来看看 iPhone 中数据库的使用方法。iPhone 中使用名为 SQLite 的数据库管理系统。它是一款轻型的数据库，是遵守ACID的关联式数据库管理系统，它的设计目标是?#24230;?#24335;?#27169;?#32780;且目前已经在很多?#24230;?#24335;产?#20998;?#20351;用了它，它占用资源非常的低，在?#24230;?#24335;设备中，可能只需要几百K的内存就够了。它能够支持Windows/Linux/Unix等等主流的操作系统，同时能够跟很多程序语言相结合，比如Tcl、PHP、Java等，还有ODBC接口，同样比起Mysql、PostgreSQL这两款开源世界著名的数据库管理系统来讲，它的处理速度比他们都快。 其使用步骤大致分为以下几步： 1 创建DB文件和表格 2 添加必须的库文件(FMDB for iPhone, libsqlite3.0.dylib) 3 通过 FMDB 的方法使用 SQLite 创建DB文件和表格 1 2 3 4 5 $ sqlite3 sample.db sqlite> CREATE TABLE TEST( .> id INTEGER PRIMARY KEY, .> name VARCHAR(255) .> ); 简单地使用上面的语句生成数据库文件后，用一个图形化SQLite管理工具，比如 Lita 来管理还是很方便的。 然后将文件(sample.db)添加到工程中。 添加必须的库文件(FMDB for iPhone, libsqlite3.0.dylib) 首先添加 Apple 提供的 sqlite 操作用程序库 ibsqlite3.0.dylib 到工程中。 位置如下 /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS${VER}.sdk/usr/lib/libsqlite3.0.dylib 这样一来就可以访问数据库了，但是为了更加方便的操作数据库，这里使用 FMDB for iPhone。 1 svn co http://flycode.googlecode.com/svn/trunk/fmdb fmdb 如上下载该库，并将以下文件添加到工程文件中： FMDatabase.h FMDatabase.m FMDatabaseAdditions.h FMDatabaseAdditions.m FMResultSet.h FMResultSet.m 通过 FMDB 的方法使用 SQLite 使用 SQL 操作数据库的代码在程序库的 fmdb.m 文件中大部分都列出了、只是连接数据库文件的时候需要注意 — 执行的时候，参照的数据库路径位于 Document 目录下，之前把刚才的 sample.db 文件拷贝过去就好了。 位置如下 /Users/xxxx/Library/Application Support/iPhone Simulator/User/Applications/xxxx/Documents/sample.db 以下为链接数据库时的代码： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 BOOL success; NSError *error; NSFileManager *fm = [NSFileManager defaultManager]; NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@“sample.db“]; success = [fm fileExistsAtPath:writableDBPath]; if(!success){ NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@“sample.db“]; success = [fm copyItemAtPath:defaultDBPath toPath:writableDBPath error: if(!success){ NSLog([error localizedDescription]); } } //连接DB FMDatabase* db = [FMDatabase databaseWithPath:writableDBPath]; if ([db open]) { [db setShouldCacheStatements:YES]; //INSERT [db beginTransaction]; int i = 0; while (i++ CREATE TABLE TbNote( .> id INTEGER PRIMARY KEY, .> title VARCHAR(255), .> body VARCHAR(255) .> ); 创建DTO（Data Transfer Object） 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 //TbNote.h #import @interface TbNote : NSObject { int index; NSString *title; NSString *body; } @property (nonatomic, retain) NSString *title; @property (nonatomic, retain) NSString *body; - (id)initWithIndex:(int)newIndex Title:(NSString *)newTitle Body:(NSString *)newBody; - (int)getIndex; @end //TbNote.m #import “TbNote.h“ @implementation TbNote @synthesize title, body; - (id)initWithIndex:(int)newIndex Title:(NSString *)newTitle Body:(NSString *)newBody{ if(self = [super init]){ index = newIndex; self.title = newTitle; self.body = newBody; } return self; } - (int)getIndex{ return index; } - (void)dealloc { [title release]; [body release]; [super dealloc]; } @end 创建DAO（Data Access Objects） 这里将 FMDB 的函数调用封装为 DAO 的方式。 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 //BaseDao.h #import @class FMDatabase; @interface BaseDao : NSObject { FMDatabase *db; } @property (nonatomic, retain) FMDatabase *db; -(NSString *)setTable:(NSString *)sql; @end //BaseDao.m #import “SqlSampleAppDelegate.h“ #import “FMDatabase.h“ #import “FMDatabaseAdditions.h“ #import “BaseDao.h“ @implementation BaseDao @synthesize db; - (id)init{ if(self = [super init]){ //由 AppDelegate 取得打开的数据库 SqlSampleAppDelegate *appDelegate = (SqlSampleAppDelegate *)[[UIApplication sharedApplication] delegate]; db = [[appDelegate db] retain]; } return self; } //子类中实现 -(NSString *)setTable:(NSString *)sql{ return NULL; } - (void)dealloc { [db release]; [super dealloc]; } @end 下面是访问 TbNote 表格的类。 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 //TbNoteDao.h #import #import “BaseDao.h“ @interface TbNoteDao : BaseDao { } -(NSMutableArray *)select; -(void)insertWithTitle:(NSString *)title Body:(NSString *)body; -(BOOL)updateAt:(int)index Title:(NSString *)title Body:(NSString *)body; -(BOOL)deleteAt:(int)index; @end //TbNoteDao.m #import “FMDatabase.h“ #import “FMDatabaseAdditions.h“ #import “TbNoteDao.h“ #import “TbNote.h“ @implementation TbNoteDao -(NSString *)setTable:(NSString *)sql{ return [NSString stringWithFormat:sql, @“TbNote“]; } //SELECT -(NSMutableArray *)select{ NSMutableArray *result = [[[NSMutableArray alloc] initWithCapacity:0] autorelease]; FMResultSet *rs = [db executeQuery:[self setTable:@“SELECT * FROM %@“]]; while ([rs next]) { TbNote *tr = [[TbNote alloc] initWithIndex:[rs intForColumn:@“id“] Title:[rs stringForColumn:@“title“] Body:[rs stringForColumn:@“body“] ]; [result addObject:tr]; [tr release]; } [rs close]; return result; } //INSERT -(void)insertWithTitle:(NSString *)title Body:(NSString *)body{ [db executeUpdate:[self setTable:@“INSERT INTO %@ (title, body) VALUES (?,?)“], title, body]; if ([db hadError]) { NSLog(@“Err %d: %@“, [db lastErrorCode], [db lastErrorMessage]); } } //UPDATE -(BOOL)updateAt:(int)index Title:(NSString *)title Body:(NSString *)body{ BOOL success = YES; [db executeUpdate:[self setTable:@“UPDATE %@ SET title=?, body=? WHERE id=?“], title, body, [NSNumber numberWithInt:index]]; if ([db hadError]) { NSLog(@“Err %d: %@“, [db lastErrorCode], [db lastErrorMessage]); success = NO; } return success; } //DELETE - (BOOL)deleteAt:(int)index{ BOOL success = YES; [db executeUpdate:[self setTable:@“DELETE FROM %@ WHERE id = ?“], [NSNumber numberWithInt:index]]; if ([db hadError]) { NSLog(@“Err %d: %@“, [db lastErrorCode], [db lastErrorMessage]); success = NO; } return success; } - (void)dealloc { [super dealloc]; } @end 为了确认程序正确，我们添加一个 UITableView。使用 initWithNibName 测试 DAO。 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 //NoteController.h #import @class TbNoteDao; @interface NoteController : UIViewController { UITableView *myTableView; TbNoteDao *tbNoteDao; NSMutableArray *record; } @property (nonatomic, retain) UITableView *myTableView; @property (nonatomic, retain) TbNoteDao *tbNoteDao; @property (nonatomic, retain) NSMutableArray *record; @end //NoteController.m #import “NoteController.h“ #import “TbNoteDao.h“ #import “TbNote.h“ @implementation NoteController @synthesize myTableView, tbNoteDao, record; - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { tbNoteDao = [[TbNoteDao alloc] init]; [tbNoteDao insertWithTitle:@“TEST TITLE“ Body:@“TEST BODY“]; // [tbNoteDao updateAt:1 Title:@“UPDATE TEST“ Body:@“UPDATE BODY“]; // [tbNoteDao deleteAt:1]; record = [[tbNoteDao select] retain]; } return self; } - (void)viewDidLoad { [super viewDidLoad]; myTableView = [[UITableView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; myTableView.delegate = self; myTableView.dataSource = self; self.view = myTableView; } - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [record count]; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @“Cell“; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease]; } TbNote *tr = (TbNote *)[record objectAtIndex:indexPath.row]; cell.text = [NSString stringWithFormat:@“%i %@“, [tr getIndex], tr.title]; return cell; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; } - (void)dealloc { [super dealloc]; } @end 最后我们开看看连接DB，和添加 ViewController 的处理。这一同样不使用 Interface Builder。 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 //SqlSampleAppDelegate.h #import @class FMDatabase; @interface SqlSampleAppDelegate : NSObject { UIWindow *window; FMDatabase *db; } @property (nonatomic, retain) IBOutlet UIWindow *window; @property (nonatomic, retain) FMDatabase *db; - (BOOL)initDatabase; - (void)closeDatabase; @end //SqlSampleAppDelegate.m #import “SqlSampleAppDelegate.h“ #import “FMDatabase.h“ #import “FMDatabaseAdditions.h“ #import “NoteController.h“ @implementation SqlSampleAppDelegate @synthesize window; @synthesize db; - (void)applicationDidFinishLaunching:(UIApplication *)application { if (![self initDatabase]){ NSLog(@“Failed to init Database.“); } NoteController *ctrl = [[NoteController alloc] initWithNibName:nil bundle:nil]; [window addSubview:ctrl.view]; [window makeKeyAndVisible]; } - (BOOL)initDatabase{ BOOL success; NSError *error; NSFileManager *fm = [NSFileManager defaultManager]; NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@“sample.db“]; success = [fm fileExistsAtPath:writableDBPath]; if(!success){ NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@“sample.db“]; success = [fm copyItemAtPath:defaultDBPath toPath:writableDBPath error: if(!success){ NSLog([error localizedDescription]); } success = NO; } if(success){ db = [[FMDatabase databaseWithPath:writableDBPath] retain]; if ([db open]) { [db setShouldCacheStatements:YES]; }else{ NSLog(@“Failed to open database.“); success = NO; } } return success; } - (void) closeDatabase{ [db close]; } - (void)dealloc { [db release]; [window release]; [super dealloc]; } @end