IOS CoreData 多表查询demo解析

在IOS CoreData中，多表查询上相对来说，没有SQL直观，但CoreData的功能还是可以完成相关操作的。

下面使用CoreData进行关系数据库的表与表之间的关系演示。生成CoreData和如何设置关系就不再详谈了，见之前的文章。

建立好的关系图：

一步步建立上面关系图：

员工表: 

部门表:

职位表:

工资等级表:

开户银行表:

 

建立表之后，我们还需要建立表之间的关系

部门和员工之间的关系：1 ->  N

部门和职位的关系：1  ->  N

职位与员工的关系：1 ->  N

开户行与员工：一个员工只能提供一个开户行，但一个开户行可以给多名员工进行开卡。所以关系为1 -> N；

 

职位和工资等级：一个职位只对应一个工资等级；1  -  1

IOS CoreData 多表查询demo解析(二)－－插入测试数据

下面插入测试数据：

Department *dept1 = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:self.managedObjectContext];

    dept1.dp_deptname = @"HR";

    

    Department *dept2 = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:self.managedObjectContext];

    dept2.dp_deptname = @"DEV";

    

    Department *dept3 = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:self.managedObjectContext];

    dept3.dp_deptname = @"POD";

    

    

    Salary *sy1 =[NSEntityDescription insertNewObjectForEntityForName:@"Salary" inManagedObjectContext:self.managedObjectContext];

    sy1.sy_level = @"D";

    sy1.sy_scale = 0.1;//[NSNumber numberWithDouble:0.1];

    

    Salary *sy2 =[NSEntityDescription insertNewObjectForEntityForName:@"Salary" inManagedObjectContext:self.managedObjectContext];

    sy2.sy_level = @"C";

    sy2.sy_scale = 0.15;//[NSNumber numberWithDouble:0.15];

    

    Salary *sy3 =[NSEntityDescription insertNewObjectForEntityForName:@"Salary" inManagedObjectContext:self.managedObjectContext];

    sy3.sy_level = @"B";

    sy3.sy_scale = 0.4;//[NSNumber numberWithDouble:0.4];

    

    Salary *sy4 =[NSEntityDescription insertNewObjectForEntityForName:@"Salary" inManagedObjectContext:self.managedObjectContext];

    sy4.sy_level = @"A";

    sy4.sy_scale = 0.8;//[NSNumber numberWithDouble:0.8];

    

    Post *pt1 = [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt1.pt_name = @"行政专员";

    pt1.dept = dept1;

    pt1.salary = sy2;

    

    Post *pt2 = [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt2.pt_name = @"人事经理";

    pt2.dept = dept1;

    pt2.salary = sy3;

    

    Post *pt3 = [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt3.pt_name = @"开发工程师";

    pt3.dept = dept2;

    pt3.salary = sy2;

    

    Post *pt4 = [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt4.pt_name = @"架构师";

    pt4.dept = dept2;

    pt4.salary = sy3;

    

    Post *pt5 = [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt5.pt_name = @"项目经理";

    pt5.dept =dept2;

    pt5.salary = sy3;

    

    Post *pt6= [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt6.pt_name = @"测试工程师";

    pt6.dept = dept2;

    pt6.salary = sy1;

    

    Post *pt7 = [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt7.pt_name = @"销售代表";

    pt7.dept = dept3;

    pt7.salary = sy1;

    

    Post *pt8 = [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt8.pt_name = @"销售经理";

    pt8.dept = dept3;

    pt8.salary = sy2;

    

    Post *pt9= [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

    pt9.pt_name = @"大客户经理";

    pt9.dept = dept3;

    pt9.salary = sy4;

    

    

    Bank *bk1 = [NSEntityDescription insertNewObjectForEntityForName:@"Bank" inManagedObjectContext:self.managedObjectContext];

    bk1.bk_name = @"招行";

    bk1.bk_address = @"广州";

    

    Bank *bk2 = [NSEntityDescription insertNewObjectForEntityForName:@"Bank" inManagedObjectContext:self.managedObjectContext];

    bk2.bk_name = @"浦发";

    bk2.bk_address = @"上海";

    

    Bank *bk3 = [NSEntityDescription insertNewObjectForEntityForName:@"Bank" inManagedObjectContext:self.managedObjectContext];

    bk3.bk_name = @"工行";

    bk3.bk_address = @"深圳";

    

    Employee *em1 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em1.em_age = 20;//[NSNumber numberWithInt:20];

    em1.em_name = @"张三";

    em1.em_sex = 1;//[NSNumber numberWithInt:1];

    em1.em_bankcardid = @"46326587439043";

    em1.dept = dept1;

    em1.post = pt1;

    em1.bank = bk3;

    

    Employee *em2 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em2.em_age = 18;//[NSNumber numberWithInt:18];

    em2.em_name = @"李四";

    em2.em_sex = 2;//[NSNumber numberWithInt:2];

    em2.em_bankcardid = @"32565443246567";

    em2.dept = dept1;

    em2.post = pt2;

    em2.bank = bk3;

    

    Employee *em3 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em3.em_age = 26;//[NSNumber numberWithInt:26];

    em3.em_name = @"欧文";

    em3.em_sex = 2;//[NSNumber numberWithInt:2];

    em3.em_bankcardid = @"14354654656767";

    em3.dept = dept2;

    em3.post = pt3;

    em3.bank = bk2;

    

    Employee *em4 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em4.em_age = 22;//[NSNumber numberWithInt:22];

    em4.em_name = @"张三";

    em4.em_sex = 2;//[NSNumber numberWithInt:2];

    em4.em_bankcardid = @"9873425837433";

    em4.dept = dept2;

    em4.post = pt4;

    em4.bank = bk2;

    

    Employee *em5 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em5.em_age = 28;//[NSNumber numberWithInt:18];

    em5.em_name = @"李四";

    em5.em_sex = 1;//[NSNumber numberWithInt:2];

    em5.em_bankcardid = @"32565743246567";

    em5.dept = dept2;

    em5.post = pt5;

    em5.bank = bk3;

    

    Employee *em6 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em6.em_age = 21;//[NSNumber numberWithInt:26];

    em6.em_name = @"欧阳";

    em6.em_sex = 1;//[NSNumber numberWithInt:2];

    em6.em_bankcardid = @"14354614656767";

    em6.dept = dept2;

    em6.post = pt6;

    em6.bank = bk1;

    

    Employee *em7 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em7.em_age = 22;//[NSNumber numberWithInt:22];

    em7.em_name = @"王飞";

    em7.em_sex = 2;//[NSNumber numberWithInt:2];

    em7.em_bankcardid = @"9878429837433";

    em7.dept = dept3;

    em7.post = pt7;

    em7.bank = bk1;

    

    Employee *em8 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em8.em_age = 26;//[NSNumber numberWithInt:18];

    em8.em_name = @"张前";

    em8.em_sex = 1;//[NSNumber numberWithInt:2];

    em8.em_bankcardid = @"32565443246167";

    em8.dept = dept3;

    em8.post = pt8;

    em8.bank = bk2;

    

    Employee *em9 = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    em9.em_age = 21;//[NSNumber numberWithInt:26];

    em9.em_name = @"谢阳";

    em9.em_sex = 1;//[NSNumber numberWithInt:2];

    em9.em_bankcardid = @"14354694656767";

    em9.dept = dept3;

    em9.post = pt9;

    em9.bank = bk1;

 

    [self saveContext];

 

数据库中数据:

 

 

 

 

1、查询 HR 部门的张三

    //查询 开发部门中张三的工资等级

    NSLog(@"----------查询 开发部门中张三的工资等级----------");

    NSLog(@"----------第1种方法----------");

    //第1种方法

    NSEntityDescription * emEty = [NSEntityDescription entityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    NSFetchRequest *frq = [[NSFetchRequest alloc]init];

    

    [frq setEntity:emEty];

    

    NSPredicate * cdt = [NSPredicate predicateWithFormat:@"em_name = %@", @"张三"];

    

    [frq setPredicate:cdt];

    

    NSArray *objs =[self.managedObjectContext executeFetchRequest:frq error:nil];

    

    NSPredicate * filter = [NSPredicate predicateWithFormat:@"dept.dp_deptname = %@",@"HR"];

    NSArray * ret = [objs filteredArrayUsingPredicate:filter];

    

    Employee* r = (Employee*)[ret lastObject];

    NSLog(@"%@", r.em_name);

    NSLog(@"%d", r.em_age);

    NSLog(@"%d", r.em_sex);

    NSLog(@"%@", r.em_bankcardid);

    NSLog(@"%@", r.post.salary.sy_level);

    NSLog(@"%f", r.post.salary.sy_scale);

    NSLog(@"%@", r.bank.bk_name);

    NSLog(@"%@", r.bank.bk_address);

    

    //[self.managedObjectContext deleteObject:r];

    //[self saveContext];

    

    NSLog(@"----------第2种方法----------");

    //第2种方法

    NSEntityDescription * emEty1 = [NSEntityDescription entityForName:@"Department" inManagedObjectContext:self.managedObjectContext];

    NSFetchRequest *frq1 = [[NSFetchRequest alloc]init];

    

    [frq1 setEntity:emEty1];

    

    NSPredicate * cdt1 = [NSPredicate predicateWithFormat:@"dp_deptname = %@", @"HR"];

    

    [frq1 setPredicate:cdt1];

    

    Department *objs1 =[[self.managedObjectContext executeFetchRequest:frq1 error:nil] lastObject];

    NSSet * ret1 = objs1.employeeship;

    

    NSPredicate * filter1 = [NSPredicate predicateWithFormat:@"em_name = %@",@"张三"];

    

    Employee* r1 = [[ret1 filteredSetUsingPredicate:filter1] anyObject];

    NSLog(@"%@", r1.em_name);

    NSLog(@"%d", r1.em_age);

    NSLog(@"%d", r1.em_sex);

    NSLog(@"%@", r1.em_bankcardid);

    

    NSLog(@"%@", r1.post.salary.sy_level);

    NSLog(@"%f", r1.post.salary.sy_scale);

    NSLog(@"%@", r1.bank.bk_name);

    NSLog(@"%@", r1.bank.bk_address);

 

 

2、查询 运维部欧阳

 

//查询运维部名为欧阳的工资等级及开户银行

    NSLog(@"----------查询运维部名为欧阳的工资等级及开户银行----------");

    NSLog(@"----------第1种方法----------");

    //第1种方法

    NSEntityDescription * entity = [NSEntityDescription entityForName:@"Employee" inManagedObjectContext:self.managedObjectContext];

    NSFetchRequest *fetch = [[NSFetchRequest alloc] init];

    

    [fetch setEntity:entity];

    

    NSPredicate * qcmd = [NSPredicate predicateWithFormat:@"em_name = %@ ",@"欧阳"];

    

    [fetch setPredicate:qcmd];

    

    NSArray * obs = [self.managedObjectContext executeFetchRequest:fetch error:nil];

    

    NSPredicate * filter2 = [NSPredicate predicateWithFormat:@"dept.dp_deptname = %@",@"DEV"];

    

    NSArray * ret2 = [obs filteredArrayUsingPredicate:filter2];  //从数组中进行过滤。

    Employee* r2 = [ret2 lastObject];

    NSLog(@"%@", r2.em_name);

    NSLog(@"%d", r2.em_age);

    NSLog(@"%d", r2.em_sex);

    NSLog(@"%@", r2.em_bankcardid);

    NSLog(@"%@", r2.post.salary.sy_level);

    NSLog(@"%f", r2.post.salary.sy_scale);

    NSLog(@"%@", r2.bank.bk_name);

    NSLog(@"%@", r2.bank.bk_address);

    

    NSLog(@"----------第2种方法----------");

    //第2种方法

    NSEntityDescription * emEty3 = [NSEntityDescription entityForName:@"Department" inManagedObjectContext:self.managedObjectContext];

    NSFetchRequest *frq3 = [[NSFetchRequest alloc]init];

    

    [frq3 setEntity:emEty3];

    

    NSPredicate * cdt3 = [NSPredicate predicateWithFormat:@"dp_deptname = %@", @"DEV"];

    

    [frq3 setPredicate:cdt3];

    

    Department *objs3 =[[self.managedObjectContext executeFetchRequest:frq3 error:nil] lastObject];

    NSSet * ret3 = objs3.employeeship;

    NSPredicate * filter3 = [NSPredicate predicateWithFormat:@"em_name = %@",@"欧阳"];

    

    Employee* r3 = [[ret3 filteredSetUsingPredicate:filter3] anyObject];

    NSLog(@"%@", r3.em_name);

    NSLog(@"%d", r3.em_age);

    NSLog(@"%d", r3.em_sex);

    NSLog(@"%@", r3.em_bankcardid);

    NSLog(@"%@", r3.post.salary.sy_level);

    NSLog(@"%f", r3.post.salary.sy_scale);

    NSLog(@"%@", r3.bank.bk_name);

    NSLog(@"%@", r3.bank.bk_address);

 多表查询主要就在于表之间建立好相关的关联关系（relationship），其次就是充分的使用NSPredicate这个查询条件来进行过滤。