sqllite数据库操作帮助类

1、基于框架FMDatabase。

2、连接类

#import <Foundation/Foundation.h>
#import "FMDatabase.h"

@interface DbHelper : NSObject {
    FMDatabase *db;
}
- (BOOL)initDatabase;
- (void)closeDatabase;
- (FMDatabase *)getDatabase;

@end


#import "DbHelper.h"
#define DB_NAME @"menu.db"

@implementation DbHelper

- (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:DB_NAME];
    
    success = [fm fileExistsAtPath:writableDBPath];
    
    if(!success){
        NSString *defaultDBPath = [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:DB_NAME];
        NSLog(@"%@",defaultDBPath);
        success = [fm copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error];
        if(!success){
            NSLog(@"error: %@", [error localizedDescription]);
        }
        success = YES;
        NSLog(@"Success to open database.");
    }
    
    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];
}

- (FMDatabase *)getDatabase
{
    if ([self initDatabase]){
        return db;
    }    
    return NULL;
}

- (void)dealloc
{
    [self closeDatabase];
    [db release];
    [super dealloc];
}
@end

3、调用

-(BOOL) UpdataData:(NSArray *)list
{
    DbHelper *dbhelper=[[DbHelper alloc] init];
    FMDatabase *db=[dbhelper getDatabase];
    [db beginTransaction];
    
    [db executeUpdate: @"DELETE FROM DishType"];
    if ([db hadError]) {
      	NSLog(@"Err %d: %@", [db lastErrorCode], [db lastErrorMessage]);
      	[db rocback];
    }
    for(id model in list)
    {
        [self insertWithModel:model db:db];
    }
  [db commit];
  [dbhelper release];
} 
        -(BOOL) insertWithModel:(DishTypeModel *) model db:(FMDatabase *) db { 	[db executeUpdate: @"INSERT INTO DishType(ID,Name,Img,Sequence) VALUES(?,?,?,?)", 	model.ID,model.Name,model.Img,model.Sequence]; 	 if ([db hadError]) {       NSLog(@"Err %d: %@", [db lastErrorCode], [db lastErrorMessage]); 	  [db rockback]; 	  return false;     } 	return true; }