OC-UI阶段学习42-FMDB

创建FMDatabas对象时参数为SQLite数据库文件路径，该路径可以是一下三种方法之一

1.文件路径。该文件路径无需真实存在，如果不存在会自动创建

2.空字符串@”“，表示会在临时目录创建一个空的数据库，当FMDatabase连接关闭时，文件也会被删除。

3.NULL。将创建一个内在数据库，同样，当FMDatabase连接关闭时，数据将被销毁

FMDB的使用

//得到沙盒地址方法
-(NSString*)sandBox
{
    NSArray *docArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *path = docArray[0];
    NSString *filePath = [path stringByAppendingPathComponent:@"fmdb.sqlite"];

    return filePath;
}

//fmdb打开数据库和建表
-(void)openAndCreat
{
    //得到数据库对象
    FMDatabase *db = [FMDatabase databaseWithPath:[self sandBox]];

    BOOL isOpen = [db open];
    if (isOpen) {
        NSLog(@"db ok");
        //建表，所有无返回集的操作都可以用update来执行sql语句，返回值为bool，判断操作成功
        BOOL isCreat = [db executeUpdate:@"CREATE TABLE IF NOT EXISTS myFMDB (id integer PRIMARY KEY AUTOINCREMENT,name text NOT NULL,age integer NOT NULL DEFAULT 0)"];
        if (isCreat) {
            NSLog(@"table ok");
        }
        else
        {//建表失败
            [db lastError];
            NSLog(@"table fs");
        }
    }
    else
    {
        NSLog(@"db fs");
    }
}

//增加数据
-(void)insertData
{
    //得到实例对象
    FMDatabase *db = [FMDatabase databaseWithPath:[self sandBox]];
    //先关闭
    [db close];
    if ([db open]) {
        //打开成功，插入数据
        NSInteger age = [_ageTextField.text integerValue];
        //两种方式
        //使用update传参，占位符为?，参数值必须为对象
        BOOL isExe = [db executeUpdate:@"INSERT INTO myFMDB (name,age)values(?,?)",_nameTextField.text,@(age)];
        //使用updateWithFormat，占位符%@等
        BOOL isExe2 = [db executeUpdateWithFormat:@"INSERT INTO myFMDB (name,age)values(%@,%d)",@"王",11];
        if (isExe && isExe2) {
            NSLog(@"insert ok");
        }
    }
}

//搜索方法
-(void)queryData
{
    FMDatabase *db = [FMDatabase databaseWithPath:[self sandBox]];
    [db open];
    //执行查询
    FMResultSet *result = [db executeQuery:@"SELECT * FROM myFMDB"];
   //存储查询结果
    _resultMArray = [[NSMutableArray alloc]init];

    //循环获得结果集
    //next 为ture时继续取下一条
    while ([result next]) {
        NSString *name = [result stringForColumn:@"name"];
        NSInteger age = [result intForColumn:@"age"];
        NSInteger id = [result intForColumn:@"id"];

        NSLog(@"id = %ld,name = %@,age = %ld",id,name,age);
        NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:name,@"name",@(age),@"age",@(id),@"id",nil];
        [_resultMArray addObject:dic];
    }

    //释放结果集
    [result close];

    //搜索表里的记录数
    [db executeQuery:@"select count(*) from myFMDB"];

    //关数据库
    [db close];

}

//单个字段值的查询
-(void)querySumRow
{
    FMDatabase *db = [FMDatabase databaseWithPath:[self sandBox]];
    if ([db open]) {
        int sumRow = [db intForQuery:@"select age from myFMDB where id = 5"];
        int sumRow2 = [db intForQuery:@"select count(*) from myFMDB"];
        NSLog(@"%d,%d",sumRow,sumRow2);
    }   
}

FMDB多线程方法

//调用多线程方法
-(void)beginThread
{
    NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
    [formatter setDateFormat:@"yy-MM-dd,hh:mm:ss.SSS"];
    //开始时间
    NSLog(@"%@",[formatter stringFromDate:[NSDate date]]);
    //建表
    [self createSecondTable];
    //两种方法
        [self threads];
    // [self threadsSecond];不使用事务

    //插入操作
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        [self threadsSecond];
        NSLog(@"%@",[NSThread currentThread]);
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"这里是主线程--%@",[NSThread currentThread]);
        });
    });

    //结束时间
    NSLog(@"%@",[formatter stringFromDate:[NSDate date]]);

}

#pragma mark -- 多线程

-(void)threads
{
    //创建队列
    FMDatabaseQueue *queue = [FMDatabaseQueue databaseQueueWithPath:[self sandBox]];

    __block BOOL isError = NO;
    //使用事务的方式处理多个操作,不需要手动打开或关闭数据库
    [queue inTransaction:^(FMDatabase *db, BOOL *rollback) {
        //回滚，从错误操作开始回滚到正确的操作
        for (int i = 0 ; i < 100000; i++) {
            NSString *sql = @"insert into stu (name,age,gender)values(?,?,?);";
            //插入操作
            isError = [db executeUpdate:sql,@"飞燕",@(i),@"女"];
        }
        if (!isError) {
            NSLog(@"insert fs");
            *rollback = YES;//插入出错，回滚到上次正确的地方;
        }

    }];
}

//不使用事物处理多线程
-(void)threadsSecond
{
    //得到队列
    FMDatabaseQueue *queue = [FMDatabaseQueue databaseQueueWithPath:[self sandBox]];

    __block BOOL isError = NO;
    //不使用事务的多线程操作
    [queue inDatabase:^(FMDatabase *db) {
// [db beginTransaction];//开始事务
        for (int i = 0 ; i < 1000; i++) {
            NSString *sql = @"insert into stu (name,age,gender)values(?,?,?);";
            //插入操作
            isError = [db executeUpdate:sql,@"飞燕",@(i),@"女"];
        }
        if (!isError) {
            NSLog(@"insert fs");
        }

// [db commit];//事务提交

        NSLog(@"%@",[NSThread currentThread]);
    }];
    //上面是gcd同步队列
    //关闭动画
    dispatch_async(dispatch_get_main_queue(), ^{
        //刷新UI要写在主线程
        [self.loadV stopAnimation];        
    });
}