FMDB基本操作

1、以前使用数据库，因为一般就建立一张表，所以都是自己写代码创建，没用过fmdb,这次因为项目中涉及聊天模块，需要多张表格和数据库保存聊天记录

按照以前方法不好操作，就研究了下fmdb,发现确实挺方便的。FMDB下载地址：https://github.com/ccgus/fmdb。

2、导入FMDB文件，再导入libsqlite3.tbd依赖包。

    //创建打开数据库
    NSString *path = [self getDBPath:@"student"];//如果名称为空 数据库断开时会删除
    DDb = [FMDatabase databaseWithPath:path];
    
    [self createTable:@"95230"]; //建表
    [self insertDate:@"95230"];  //添加数据
    [self updataWithTable:@"95230"]; //修改
    [self deledataWith:@"95230"]; //删除
    [self chaxunWith:@"95230"]; //查询
    
    NSLog(@"%@/Documents",NSHomeDirectory()); //模拟器运行时 打开Documents查看数据库文件

//查询数据库
-(void)chaxunWith:(NSString *)tabname
{
    if ([DDb open]) {
//        NSString *sql = [NSString stringWithFormat:@"select * from '%@' where age = '%@'",tabname,@"18"];//
        NSString *sql = [NSString stringWithFormat:@"select * from '%@'",tabname];
        FMResultSet * rs = [DDb executeQuery:sql];
        while ([rs next]) {
            NSString * name = [rs stringForColumn:@"name"];
            int age = [rs intForColumn:@"age"];
            NSData *imgdata = [rs dataForColumn:@"image"];
            NSLog(@"%@ - %i",name,age);
        }
        [DDb close];
    }
}

//删除数据
-(void)deledataWith:(NSString *)tabname
{
    if ([DDb open]) {
        NSString *sql = [NSString stringWithFormat:@"delete from '%@' where %@ = '%@'",tabname,@"age",@"19"];
        BOOL dele = [DDb executeUpdate:sql];
        if (!dele) {
            NSLog(@"delete fail");
        }
        [DDb close];
    }
}

//修改数据
-(void)updataWithTable:(NSString *)tabname
{
    if ([DDb open]) {
        NSString *sql = [NSString stringWithFormat:@"update '%@' set %@ = '%@' where age = '%@'",tabname,@"name",@"张86",@"18"];
        BOOL update =[DDb executeUpdate:sql];
        if (!update) {
            NSLog(@"update fail");
        }
        [DDb close];
    }
}

//添加数据
-(void)insertDate:(NSString *)tabname
{
    if ([DDb open])
    {
        NSString *bb = [NSString stringWithFormat:@"INSERT INTO '%@' (name, age, image) VALUES (?,?,?)",tabname];
//        UIImage *img = [UIImage imageNamed:@"test"];
//        NSData *imgdata = UIImagePNGRepresentation(img);
        BOOL insert = [DDb executeUpdate:bb,@"小三",@"20",[NSData data]];
        if (!insert) {
            NSLog(@"insert fail");
        }
        [DDb close];
    }
}
//创建数据库表格
-(void)createTable:(NSString *)tabname
{
    if ([DDb open]) {
        //判断表名是否为纯数字
        NSString *sqlCreateTable =  [NSString stringWithFormat:@"create table if not exists '%@' (id INTEGER PRIMARY KEY AUTOINCREMENT, name text,age integer, image blob)",tabname];         BOOL res = [DDb executeUpdate:sqlCreateTable];
        if (!res) {
            NSLog(@"创建表格失败");
        }
        [DDb close];
    }
}

//创建数据库
-(NSString *)getDBPath:(NSString *)curname
{
    curname = [NSString stringWithFormat:@"%@.sqlite",curname];
    NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *DBPath = [documentPath stringByAppendingPathComponent:curname];
    return DBPath;
}

注：FMDB写入图片数据NSData时候，图片转换成数据流用 UIImageJPEGRepresentation( img , float); 如果用 UIImagePNGRepresentation转的话，写入数据库时间会变长，

我5张图片没有压缩转写入数据库时间需要花费1.5秒，而且是写入任何一个参数都要1.5秒。

>>>>> 其他比较详细的FMDB使用介绍。

=====> http://m.blog.csdn.net/article/details?id=7204625

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FMDB基本操作

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