IOS之数据库的查找，删除，添加，更新

DB类之.h文件
#import <Foundation/Foundation.h>
#import <sqlite3.h>

@interface DB : NSObject
+(sqlite3 *)openDB;//打开数据库
-(void)closeDB;//关闭数据库

@end

DB类之.m文件
#import "DB.h"
#import <sqlite3.h>
static sqlite3 *db = nil;
@implementation DB
+(sqlite3 *)openDB
{
    if(db)
    {
        return db;
    }
    //目标路径
    NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDirectory, YES)objectAtIndex:0];
    //原始路径
    NSString *filePath = [docPath stringByAppendingPathComponent:@"db.sqlite"];
   
    NSFileManager *fm = [NSFileManager defaultManager];
   
    if ([fm fileExistsAtPath:filePath] == NO)//如果doc下没有数据库，从bundle里面拷贝过来
 
    {
        NSString *bundle = [[NSBundle mainBundle]pathForResource:@"classDB" ofType:@"sqlite"];
       
        NSError *err = nil;
       
        if ([fm copyItemAtPath:bundle toPath:filePath error:&err] == NO) //如果拷贝失败
        {
            NSLog(@"%@",[err localizedDescription]);
        }
       
       
    }
    sqlite3_open([filePath UTF8String], &db);
    return db;  
}
-(void)closeDB
{
    if (db)
    {
        sqlite3_close(db);  
    }
   
}
@end
Person类.h文件
#import <Foundation/Foundation.h>

@interface Person : NSObject
@property(nonatomic,retain)NSString *name,*phone;
@property(nonatomic,assign)int age,ID;

-(id)initWithName:(NSString *)name phone:(NSString *)phone age:(int)age ID:(int)ID;

+(NSMutableArray *)findAll;
+(int)count;
+(Person *)findByID:(int)ID;
+(NSMutableArray *)findByname:(NSString *)name;
+(void)addName:(NSString *)name  phone:(NSString *)phone age:(int)age;
+(void)deleteByID:(int)ID;
+(void)updataName:(NSString *)name phone:(NSString *)phone age:(int)age forID:(int)ID;
@end
Person类.m文件
#import "Person.h"
#import "DB.h"

@implementation Person