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第九节 用SQLite管理数据库(2)

设置字体:
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@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。
 
 //BaseDao.h
#import <Foundation/Foundation.h>
 
@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。
 //TbNoteDao.h
#import <Foundation/Foundation.h>
#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]);
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