IOS-CoreData（增删改查、表关联、分页和模糊查询、多个数据库）

1>什么是CoreData

Core Data是iOS5之后才出现的一个框架，它提供了对象-关系映射(ORM)的功能，即能够将OC对象转化成数据，保存在SQLite数据库文件中，也能够将保存在数据库中的数据还原成OC对象。在此数据操作期间，我们不需要编写任何SQL语句，这个有点类似于著名的Hibernate持久化框架，不过功能肯定是没有Hibernate强大的。

2>CoreData的使用步骤

1.创建模型文件
2.添加实体
3.创建实体类
4.生成上下文 关联模型文件生成数据库
5.保存对象到数据库
6.从数据库获取对象
7.更新数据
8.删除数据

3>打开CoreData的SQL语句输出开关

1.打开Product，点击EditScheme...
2.点击Arguments，在ArgumentsPassed On Launch中添加2项
1> -com.apple.CoreData.SQLDebug
2> 1

一、CoreData基本使用-增删改查和表关联

//
//  ViewController.m
//  IOS_0121_CoreData
//
//  Created by ma c on 16/1/21.
//  Copyright © 2016年 博文科技. All rights reserved.
//

#import "ViewController.h"
#import <CoreData/CoreData.h>
#import "Employee.h"
#import "Department.h"

@interface ViewController ()

@property (nonatomic, strong) NSManagedObjectContext *context;

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
//1.创建模型文件（相当于数据库中的表）
//2.添加实体(一张表)
//3.创建实体类（相当于模型）
//4.生成上下文，关联模型文件生成数据库

//上下文
self.context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
//模型数据文件
NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil];

//持久化存储器
//把数据保存到一个文件，而不是内存
NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];
//数据名字和路径
NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSString *sqlitePath = [path stringByAppendingPathComponent:@"company.sqlite"];
NSLog(@"%@",sqlitePath);

NSURL *url = [NSURL fileURLWithPath:sqlitePath];
[store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:nil];

self.context.persistentStoreCoordinator = store;

}
//数据库操作ADUQ （ADD、Delete、Update、Query）
#pragma mark - 添加员工
- (IBAction)addEmployee
{
Employee *emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.context];

emp.name = @"bowen";
emp.height = @"180";
emp.birthday = [NSDate date];

//直接保存
NSError *error = nil;
[self.context save:&error];

if (error) {
NSLog(@"%@",error);
}
}

#pragma mark - 查询员工
- (IBAction)searchEmployee
{
//1.NSFetchRequest 抓取请求对象
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
//2.设置过滤条件
NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@",@"bowen"];
request.predicate = pre;
//3.排序
NSSortDescriptor *heightSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:YES];
request.sortDescriptors = @[heightSort];
//4.执行请求
NSError *error = nil;
NSArray *emps = [self.context executeFetchRequest:request error:&error];

if (error) {
NSLog(@"%@",error);
}

for (Employee *emp in emps) {
NSLog(@"name:%@ height:%@ birthday:%@",emp.name, emp.height, emp.birthday);
}
}

#pragma mark - 更新员工
- (IBAction)updateEmployee
{
//1.查找
//获取对象
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
//设置过滤条件
NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@",@"bowen"];
request.predicate = pre;
//执行请求
NSArray *emps = [self.context executeFetchRequest:request error:nil];

//2.更新
for (Employee *emp in emps) {
emp.height = @"200";
}
//3.保存
[self.context save:nil];
}

#pragma mark - 删除员工
- (IBAction)deleteEmployee
{
//1.查找
//获取对象
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
//设置过滤条件
NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@",@"bowen"];
request.predicate = pre;
//执行请求
NSArray *emps = [self.context executeFetchRequest:request error:nil];

//2.删除
for (Employee *emp in emps) {
[self.context deleteObject:emp];
}

//3.保存
[self.context save:nil];
}

#pragma mark - 表关联
- (IBAction)AddRelationship
{
//创建两个部门：IOS、Android
Department *IOSDepart = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:self.context];
IOSDepart.departNo = @"001";
IOSDepart.name = @"IOS";
IOSDepart.createDate = [NSDate date];

Department *AndroidDepart = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:self.context];
AndroidDepart.departNo = @"002";
AndroidDepart.name = @"Android";
AndroidDepart.createDate = [NSDate date];

//创建两个员工：bowen1，bowen2
Employee *emp1 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.context];
emp1.name = @"bowen1";
emp1.height = @"180";
emp1.birthday = [NSDate date];
emp1.depart = IOSDepart;

Employee *emp2 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.context];
emp2.name = @"bowen2";
emp2.height = @"180";
emp2.birthday = [NSDate date];
emp2.depart = AndroidDepart;

//保存
[self.context save:nil];
}

- (IBAction)searchRelationship
{
//读取IOS部门员工

//1.NSFetchRequest 抓取请求对象
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];
//2.设置过滤条件
NSPredicate *pre = [NSPredicate predicateWithFormat:@"depart.name = %@",@"IOS"];
request.predicate = pre;
//3.执行请求
NSError *error = nil;
NSArray *emps = [self.context executeFetchRequest:request error:&error];

if (error) {
NSLog(@"%@",error);
}

for (Employee *emp in emps) {
NSLog(@"name:%@ height:%@ birthday:%@",emp.name, emp.height, emp.birthday);
}

}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end

三、分页查询和模糊查询

//
//  ViewController.m
//  IOS_0121_CoreData
//
//  Created by ma c on 16/1/21.
//  Copyright © 2016年 博文科技. All rights reserved.
//

#import "ViewController.h"
#import <CoreData/CoreData.h>
#import "Employee.h"
#import "Department.h"

@interface ViewController ()

@property (nonatomic, strong) NSManagedObjectContext *context;

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
//1.创建模型文件（相当于数据库中的表）
//2.添加实体(一张表)
//3.创建实体类（相当于模型）
//4.生成上下文，关联模型文件生成数据库

//上下文
self.context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
//模型数据文件
NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil];

//持久化存储器
//把数据保存到一个文件，而不是内存
NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];
//数据名字和路径
NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSString *sqlitePath = [path stringByAppendingPathComponent:@"company.sqlite"];
NSLog(@"%@",sqlitePath);

NSURL *url = [NSURL fileURLWithPath:sqlitePath];
[store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:nil];

self.context.persistentStoreCoordinator = store;

}
//数据库操作ADUQ （ADD、Delete、Update、Query）
#pragma mark - 添加员工
- (IBAction)addEmployee
{

for (int i = 0; i < 15; i++) {
Employee *emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.context];
emp.name = [NSString stringWithFormat:@"bowen%d",i];
emp.height = [NSString stringWithFormat:@"%d",180+i];
emp.birthday = [NSDate date];

}

//直接保存
NSError *error = nil;
[self.context save:&error];

if (error) {
NSLog(@"%@",error);
}
}

#pragma mark - 分页查询
- (IBAction)pagingAndQuerying
{
//1.NSFetchRequest 抓取请求对象
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];

//2.排序
NSSortDescriptor *heightSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:YES];
request.sortDescriptors = @[heightSort];

//3.分页查询
//分页的起始索引
request.fetchOffset = 12;
//分页的条数
request.fetchLimit = 6;

//4.执行请求
NSError *error = nil;
NSArray *emps = [self.context executeFetchRequest:request error:&error];

if (error) {
NSLog(@"%@",error);
}

for (Employee *emp in emps) {
NSLog(@"name:%@ height:%@ birthday:%@",emp.name, emp.height, emp.birthday);
}
}

- (IBAction)fuzzyQuery
{
//1.NSFetchRequest 抓取请求对象
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"];

//2.排序
NSSortDescriptor *heightSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:YES];
request.sortDescriptors = @[heightSort];

//3.模糊查询
//名字以“bowen1”开头
//NSPredicate *pre = [NSPredicate predicateWithFormat:@"name BEGINSWITH %@",@"bowen1"];
//request.predicate = pre;

//名字以“1”结尾
//NSPredicate *pre = [NSPredicate predicateWithFormat:@"name ENDSWITH %@",@"1"];
//request.predicate = pre;

//名字包含“wen1”结尾
//NSPredicate *pre = [NSPredicate predicateWithFormat:@"name CONTAINS %@",@"1"];
//request.predicate = pre;

//like
//名字以“1”结尾
//NSPredicate *pre = [NSPredicate predicateWithFormat:@"name like %@",@"*wen14"];
//request.predicate = pre;

//名字以“bowen2”开头
NSPredicate *pre = [NSPredicate predicateWithFormat:@"name like %@",@"bowen2*"];
request.predicate = pre;

//4.执行请求
NSError *error = nil;
NSArray *emps = [self.context executeFetchRequest:request error:&error];

if (error) {
NSLog(@"%@",error);
}

for (Employee *emp in emps) {
NSLog(@"name:%@ height:%@ birthday:%@",emp.name, emp.height, emp.birthday);
}
}

@end

三、创建多个数据库

//
//  ViewController.m
//  IOS_0121_CoreData
//
//  Created by ma c on 16/1/21.
//  Copyright © 2016年 博文科技. All rights reserved.
//

#import "ViewController.h"
#import <CoreData/CoreData.h>
#import "Employee.h"
#import "Status.h"

@interface ViewController ()

@property (nonatomic, strong) NSManagedObjectContext *companyContext;
@property (nonatomic, strong) NSManagedObjectContext *weibocontext;

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

//一个数据库对应着一个上下文
self.companyContext = [self setupContextWithModelName:@"Company"];
self.weibocontext = [self setupContextWithModelName:@"weibo"];

}

//根据模型文件返回上下文
- (NSManagedObjectContext *)setupContextWithModelName:(NSString *)modelName
{
//1.创建模型文件（相当于数据库中的表）
//2.添加实体(一张表)
//3.创建实体类（相当于模型）
//4.生成上下文，关联模型文件生成数据库

//上下文
NSManagedObjectContext *context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];

//模型数据文件
//使用下面的方法，如果boundles为空，会把boundles里面所有的模型文件的表都放在一个数据库中
//NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil];

NSLog(@"%@",[[NSBundle mainBundle] bundlePath]);

NSURL *modelURL = [[NSBundle mainBundle] URLForResource:modelName withExtension:@"momd"];
NSManagedObjectModel *model = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];

//持久化存储器
//把数据保存到一个文件，而不是内存
NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];

//数据名字和路径
NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

NSString *sqlliteName = [NSString stringWithFormat:@"%@.sqllite",modelName];

NSString *sqlitePath = [path stringByAppendingPathComponent:sqlliteName];
NSLog(@"%@",sqlitePath);

NSURL *url = [NSURL fileURLWithPath:sqlitePath];
[store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:nil];

context.persistentStoreCoordinator = store;

return context;

}
//数据库操作ADUQ （ADD、Delete、Update、Query）
#pragma mark - 添加
- (IBAction)add
{
Employee *emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.companyContext];
emp.name = @"bowen";
emp.height = @"180";
emp.birthday = [NSDate date];

Status *status = [NSEntityDescription insertNewObjectForEntityForName:@"Status" inManagedObjectContext:self.weibocontext];
status.text = @"回家";
status.createDate = @"2015-01-28";

[self.companyContext save:nil];
[self.weibocontext save:nil];

}

#pragma mark - 查询
- (IBAction)querying
{

}

@end