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;

}