ios数据库FMDB

一、下载fmdb类库

二、添加libsqulite3.0.dylib

三、添加头文件#import "FMDB.h"

四、打开数据库

a、设置路径NSString *path = [[NSSearchPathForDirectoriesInDomainas(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]  stringByAppendingPathComponent:@"shops.sqlite"];

b、设置强引用属性 @property (nonatomic, strong) FMDatabase *db;

c、self.db =  [FMDatabase databaseWithPath:path];//返回一个数据库对象

d、打开 [self.db open];

//两个重要语句

//executeQuery:查询数据

//executeUpdate:除查询数据以外的其他操作

五、创表

[self.db execureUpdate:@"CREATE TABLE IF NOT EXISTS t_shop (if integer PRIMARY KEY, name text NOT NULL, price real);"];

六、插入数据

NSString *name = [NSString stringWithFormat:@"手机-%d",i];

[self.db executeUpdateWithFormat:@"INSERT INTO t_shop(name, price) VALUES (%@, %d);",name,arc4random()%1000];

七、读取数据

a、得到结果集

FMResultSet *set = [self.db executeQuery:@"SELECT * FROM t_shop;"];

b、不断取出数据

while(set.next){

   //获得当前所指向的数据

NSString *name = [set stringForColumn:@"name"];

double price =[set doubleForColumn:@"price"];

NSLog(@"%@  %f",name , price);

}

八、删除数据

[self.db executeUpdate:@"DELETE FROM t_SHOP WHERE price < 500;"];

九、封装数据库

a、不让控制器接触数据库，设置一个工具类ShopTool

b、设置数据模型Shop

c、在ShopTool中，将db设置成全局变量

static FMDatabase *_db;

b、初始化 +(void)initalize

.......

封装的ShopTool代码：

#import <Foundation/Foundation.h>
@class HMShop;

@interface HMShopTool : NSObject
+ (NSArray *)shops;
+ (void)addShop:(HMShop *)shop;
@end


#import "HMShopTool.h"
#import "FMDB.h"
#import "HMShop.h"

@implementation HMShopTool

static FMDatabase *_db;

+ (void)initialize
{
    // 1.打开数据库
    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"shops.sqlite"];
    _db = [FMDatabase databaseWithPath:path];
    [_db open];
    
    // 2.创表
    [_db executeUpdate:@"CREATE TABLE IF NOT EXISTS t_shop (id integer PRIMARY KEY, name text NOT NULL, price real);"];
}

+ (void)addShop:(HMShop *)shop
{
    [_db executeUpdateWithFormat:@"INSERT INTO t_shop(name, price) VALUES (%@, %f);", shop.name, shop.price];
}

+ (NSArray *)shops
{// 得到结果集
    FMResultSet *set = [_db executeQuery:@"SELECT * FROM t_shop;"];
    
    // 不断往下取数据
    NSMutableArray *shops = [NSMutableArray array];
    while (set.next) {
        // 获得当前所指向的数据
        HMShop *shop = [[HMShop alloc] init];
        shop.name = [set stringForColumn:@"name"];
        shop.price = [set doubleForColumn:@"price"];
        [shops addObject:shop];
    }
    return shops;
}
@end

控制器代码：

#import "HMViewController.h"
//#import "FMDB.h"
#import "HMShop.h"
#import "HMShopTool.h"

@interface HMViewController ()
//@property (nonatomic, strong) FMDatabase *db;
@end

@implementation HMViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    // 1.打开数据库
//    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"shops.sqlite"];
//    self.db = [FMDatabase databaseWithPath:path];
//    [self.db open];
//    
//    // 2.创表
//    [self.db executeUpdate:@"CREATE TABLE IF NOT EXISTS t_shop (id integer PRIMARY KEY, name text NOT NULL, price real);"];
    // executeQuery:查询数据
//    [self.db executeQuery:<#(NSString *), ...#>];
    
    // executeUpdate:除查询数据以外的其他操作
//    [self.db executeUpdate:<#(NSString *), ...#>];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
//    for (int i = 0; i<100; i++) {
//        HMShop *shop = [[HMShop alloc] init];
//        shop.name = [NSString stringWithFormat:@"枕头--%d", i];
//        shop.price = arc4random() % 200;
//        [HMShopTool addShop:shop];
//    }
    
    NSArray *shops = [HMShopTool shops];
    for (HMShop *shop in shops) {
        NSLog(@"%@ %f", shop.name, shop.price);
    }
    
//    [self.db executeUpdate:@"DELETE FROM t_shop WHERE price < 800;"];
//    
//    [self query];
}

shop.h模型代码：

#import <Foundation/Foundation.h>

@interface HMShop : NSObject
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) double  price;
@end