iOS数据库FMDB

iOS数据库FMDB

简介

iOS中使用C语言函数对原生SQLite数据库进行增删改查操作,复杂麻烦,于是,就出现了一系列将SQLite API封装的库,如FMDB
FMDB是针对libsqlite3框架进行封装的三方,它以OC的方式封装了SQLite的C语言的API,使用步骤与SQLite相似

Mac SQL软件 解压密码(hezibuluo.com)
链接:https://pan.baidu.com/s/1scd3HqSbRaBuPvKzlj8EGw 密码:rqye

使用

主要类型

FMDatabase:一个FMDatabase对象代表一个单独的SQLite数据库,通过SQLite语句执行数据库的增删改查操作
FMResultSet:使用FMDatabase对象查询数据库后的结果集
FMDatabaseQueue:用于多线程操作数据库,它保证线程安全

基本使用

  • 使用FMDBbase类创建数据库
//1.创建database路径
    NSString *docuPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    NSString *dbPath = [docuPath stringByAppendingPathComponent:@"test.db"];
    NSLog(@"!!!dbPath = %@",dbPath);
     //2.创建对应路径下数据库
    db = [FMDatabase databaseWithPath:dbPath];
    //3.在数据库中进行增删改查操作时,需要判断数据库是否open,如果open失败,可能是权限或者资源不足,数据库操作完成通常使用close关闭数据库
    [db open];
    if (![db open]) {
        NSLog(@"db open fail");
        return;
    }
    //4.数据库中创建表(可创建多张)
    NSString *sql = @"create table if not exists t_student ('ID' INTEGER PRIMARY KEY AUTOINCREMENT,'name' TEXT NOT NULL, 'phone' TEXT NOT NULL,'score' INTEGER NOT NULL)";
    //5.执行更新操作 此处database直接操作,不考虑多线程问题,多线程问题,用FMDatabaseQueue 每次数据库操作之后都会返回bool数值,YES,表示success,NO,表示fail,可以通过 @see lastError @see lastErrorCode @see lastErrorMessage
    BOOL result = [db executeUpdate:sql];
    if (result) {
        NSLog(@"create table success");
        
    }
    [db close];

创建的test.db数据库


test.db
  • 插入命令sql语句
/**
 增删改查中 除了查询(executeQuery),其余操作都用(executeUpdate)
 //1.sql语句中跟columnname 绑定的value 用 ?表示,不加‘’,可选参数是对象类型如:NSString,不是基本数据结构类型如:int,方法自动匹配对象类型
 - (BOOL)executeUpdate:(NSString*)sql, ...;
 //2.sql语句中跟columnname 绑定的value 用%@/%d表示,不加‘’
 - (BOOL)executeUpdateWithFormat:(NSString *)format, ... NS_FORMAT_FUNCTION(1,2);
 //3.sql语句中跟columnname 绑定的value 用 ?表示的地方依次用 (NSArray *)arguments 对应的数据替代
 - (BOOL)executeUpdate:(NSString*)sql withArgumentsInArray:(NSArray *)arguments;
 //4.同3 ,区别在于多一个error指针,记录更新失败
 - (BOOL)executeUpdate:(NSString*)sql values:(NSArray * _Nullable)values error:(NSError * _Nullable __autoreleasing *)error;
 //5.同3,区别在于用 ? 表示的地方依次用(NSDictionary *)arguments中对应的数据替代
 - (BOOL)executeUpdate:(NSString*)sql withParameterDictionary:(NSDictionary *)arguments;
 - (BOOL)executeUpdate:(NSString*)sql withVAList: (va_list)args;
 */
//0.直接sql语句
//    BOOL result = [db executeUpdate:@"insert into 't_student' (ID,name,phone,score) values(110,'x1','11',83)"];
    //1.
//    BOOL result = [db executeUpdate:@"insert into 't_student'(ID,name,phone,score) values(?,?,?,?)",@111,@"x2",@"12",@23];
    //2.
//    BOOL result = [db executeUpdateWithFormat:@"insert into 't_student' (ID,name,phone,score) values(%d,%@,%@,%d)",112,@"x3",@"13",43];
    //3.
[db open];
BOOL result = [db executeUpdate:@"insert into 't_student'(ID,name,phone,score) values(?,?,?,?)" withArgumentsInArray:@[@113,@"x3",@"13",@53]];
    if (result) {
        NSLog(@"insert into 't_studet' success");
        [self showAlertWithTitle:@"insert  success" message:nil person:nil];
    } else {
        [self showAlertWithTitle:[db lastError].description message:nil person:nil];
    }
    [db close];
  • 删除命令sql语句
[db open];
    ///0.直接sql语句
//    BOOL result = [db executeUpdate:@"delete from 't_student' where ID = 110"];
    //1.
//    BOOL result = [db executeUpdate:@"delete from 't_student' where ID = ?",@(111)];
    //2.
//    BOOL result = [db executeUpdateWithFormat:@"delete from 't_student' where ID = %d",112];
    //3.
      BOOL result = [db executeUpdate:@"delete from 't_student' where ID = ?" withArgumentsInArray:@[@113]];
    if (result) {
        NSLog(@"delete from 't_student' success");
        [self showAlertWithTitle:@"delete  success" message:nil person:nil];
    } else {
        [self showAlertWithTitle:[db lastError].description message:nil person:nil];
    }
    [db close];
  • 更新命令sql语句
[db open];
    //0.直接sql语句
//    BOOL result = [db executeUpdate:@"update 't_student' set ID = 110 where name = 'x1'"];
    //1.
//    BOOL result = [db executeUpdate:@"update 't_student' set ID = ? where name = ?",@111,@"x2" ];
    //2.
//    BOOL result = [db executeUpdateWithFormat:@"update 't_student' set ID = %d where name = %@",113,@"x3" ];
    //3.
    BOOL result = [db executeUpdate:@"update 't_student' set ID = ? where name = ?" withArgumentsInArray:@[@113,@"x3"]];
    if (result) {
        NSLog(@"update 't_student' success");
        [self showAlertWithTitle:@"update  success" message:nil person:nil];
    } else {
        [self showAlertWithTitle:[db lastError].description message:nil person:nil];
    }
    [db close];
  • 查询命令sql语句
    FMResultSet根据column name获取对应数据的方法
    • intForColumn:
    • longForColumn:
    • longLongIntForColumn:
    • boolForColumn:
    • doubleForColumn:
    • stringForColumn:
    • dateForColumn:
    • dataForColumn:
    • dataNoCopyForColumn:
    • UTF8StringForColumn:
    • objectForColumn:
[db open];
    //0.直接sql语句
//    FMResultSet *result = [db executeQuery:@"select * from 't_student' where ID = 110"];
    //1.
//    FMResultSet *result = [db executeQuery:@"select *from 't_student' where ID = ?",@111];
    //2.
//    FMResultSet *result = [db executeQueryWithFormat:@"select * from 't_student' where ID = %d",112];
    //3.
    FMResultSet *result = [db executeQuery:@"select * from 't_student' where ID = ?" withArgumentsInArray:@[@113]];
    //4
//    FMResultSet *result = [db executeQuery:@"select * from 't_sutdent' where ID = ?" withParameterDictionary:@{@"ID":@114}];
    NSMutableArray *arr = [NSMutableArray array];
    while ([result next]) {
        PersonVO *person = [PersonVO new];
        person.ID = [result intForColumn:@"ID"];
        person.name = [result stringForColumn:@"name"];
        person.phone = [result stringForColumn:@"phone"];
        person.score = [result intForColumn:@"score"];
        [arr addObject:person];
        NSLog(@"从数据库查询到的人员 %@",person.name);
        [self showAlertWithTitle:@"query  success" message:nil person:person];
        
    }

FMDB的事务

(1) 事务定义:
事务(Transaction)是并发操作的基本单位,是指单个逻辑工作单位执行的一系列操作序列,这些操作要不都成功,要不就不成功,事务是数据库维护数据一致性的单位,在每个事务结束时,都能保证数据一致性与准确性,通常事务跟程序是两个不同的概念,一个程序中包含多个事务,事务主要解决并发条件下操作数据库,保证数据
(2) 事务特征:
原子性(Atomic):事务中包含的一系列操作被看作一个逻辑单元,这个逻辑单元要不全部成功,要不全部失败
一致性(Consistency):事务中包含的一系列操作,只有合法的数据被写入数据库,一些列操作失败之后,事务会滚到最初创建事务的状态
隔离性(Isolation):对数据进行修改的多个事务之间是隔离的,每个事务是独立的,不应该以任何方式来影响其他事务
持久性(Durability)事务完成之后,事务处理的结果必须得到固化,它对于系统的影响是永久的,该修改即使出现系统固执也将一直保留,真实的修改了数据库
(3) 事务语句:

/**
 transaction:事务 开启一个事务执行多个任务,效率高
 1.fmdb 封装transaction 方法,操作简单
 - (BOOL)beginTransaction;
 - (BOOL)beginDeferredTransaction;
 - (BOOL)beginImmediateTransaction;
 - (BOOL)beginExclusiveTransaction;
 - (BOOL)commit;
 - (BOOL)rollback;
 等等
 */

开启事务 :beginTransaction
回滚事务:rollback
提交事务:commit

- (void)handleTransaction:(UIButton *)sender {
    NSString *documentPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    NSString *dbPath = [documentPath stringByAppendingPathComponent:@"test1.db"];
    FMDatabase *db = [[FMDatabase alloc]initWithPath:dbPath];
    [db open];
    if (![db isOpen]) {
        return;
    }
    BOOL result = [db executeUpdate:@"create table if not exists text1 (name text,age,integer,ID integer)"];
    if (result) {
        NSLog(@"create table success");
    }
    //1.开启事务
    [db beginTransaction];
    NSDate *begin = [NSDate date];
    BOOL rollBack = NO;
    @try {
       //2.在事务中执行任务
        for (int i = 0; i< 500; i++) {
            NSString *name = [NSString stringWithFormat:@"text_%d",I];
            NSInteger age = I;
            NSInteger ID = i *1000;
            
            BOOL result = [db executeUpdate:@"insert into text1(name,age,ID) values(:name,:age,:ID)" withParameterDictionary:@{@"name":name,@"age":[NSNumber numberWithInteger:age],@"ID":@(ID)}];
            if (result) {
                NSLog(@"在事务中insert success");
            }
        }
    }
    @catch(NSException *exception) {
        //3.在事务中执行任务失败,退回开启事务之前的状态
        rollBack = YES;
        [db rollback];
    }
    @finally {
        //4. 在事务中执行任务成功之后
        rollBack = NO;
        [db commit];
    }
    NSDate *end = [NSDate date];
    NSTimeInterval time = [end timeIntervalSinceDate:begin];
    NSLog(@"在事务中执行插入任务 所需要的时间 = %f",time);
    
}

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