FMDB简单使用

1、增删改查：//注意：dataWithPath中的路径参数一般会选择保存到沙箱中的Documents目录中；

//如果这个参数设置为nil则数据库会在内存中创建；
//如果设置为@””则会在沙箱中的临时目录创建,应用程序关闭则文件删除
//增
- (void)openDB:(NSString *)dbname{
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    path = [path stringByAppendingPathComponent:dbname];
    NSLog(@"path--->%@",path);
    FMDatabase *db = [FMDatabase databaseWithPath:path];
    _fmdb = db;
    if ([db open]) {
        NSLog(@"数据库（%@）打开成功",dbname);
        //在FMDB中，除查询以外的所有操作，都称为“更新”
        //create、drop、insert、update、delete等
        //建表
        BOOL result = [db executeUpdate:[NSString stringWithFormat:@"CREATE TABLE IF NOT EXISTS t_student (id integer PRIMARY KEY AUTOINCREMENT, name text NOT NULL, age integer NOT NULL);"]];
        if (result) {
            NSLog(@"创表成功");
        }else{
            NSLog(@"创表失败");
        }
    }else{
        NSLog(@"数据库（%@）打开失败",dbname);
    }
}
//改
- (void)insert{
    for (int i = ; i<; i++) {
        NSString *name = [NSString stringWithFormat:@"jack_%d",i];
        [self.fmdb executeUpdate:@"INSERT INTO t_student (name, age) VALUES (?, ?);", name, @(arc4random_uniform())];
    }
}
//删
- (void)delete{
    [self.fmdb executeUpdate:@"DROP TABLE IF EXISTS t_student;"];
    [self.fmdb executeUpdate:@"CREATE TABLE IF NOT EXISTS t_student (id integer PRIMARY KEY AUTOINCREMENT, name text NOT NULL, age integer NOT NULL);"];
}
//查
- (void)query
{
    // 1.执行查询语句
    FMResultSet *resultSet = [self.fmdb executeQuery:@"SELECT * FROM t_student"];

    // 2.遍历结果
    while ([resultSet next]) {
        int ID = [resultSet intForColumn:@"id"];
        NSString *name = [resultSet stringForColumn:@"name"];
        int age = [resultSet intForColumn:@"age"];
        NSLog(@"%d %@ %d", ID, name, age);
    }

//此处是调用下面的自定义models集合

    NSArray *aaa = [self executeQuery:resultSet.query withArgumentsInArray:_arr modelClass:[Person class] performBlock:^(id model, FMResultSet *rs) {
        rs = resultSet;
    }];

if (aaa.count !=0 ) {

Person *p = aaa[0];

NSLog(@"%@--%@--%d",aaa,p.name,p.age);

}else{

NSLog(@"查询生成的模型数组为空");

}

}

2、自定义构造models集合

/**
 *  执行查询操作，自定构造models集合
 *
 *  @param sql        sql语句
 *  @param args       sql参数
 *  @param modelClass 结果集model类型
 *  @param block      对model执行自定义操作
 *
 *  @return 查询结果集
 */
- (NSArray *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)args modelClass:(Class)modelClass performBlock:(void (^)(id model, FMResultSet *rs))block
{
    __block NSMutableArray *models = [NSMutableArray array];

    [_queue inDatabase:^(FMDatabase *db) {
        NSDictionary *mapping = nil;

        FMResultSet *rs = [db executeQuery:sql withArgumentsInArray:args];
        while ([rs next]) {
            id model = [[modelClass alloc] init];
            if(!mapping && [model conformsToProtocol:@protocol(ColumnPropertyMappingDelegate)]) {
                //实现了列-属性转换协议
                mapping = [model columnPropertyMapping];
            }

            for (int i = ; i < [rs columnCount]; i++) {
                //列名
                NSString *columnName = [rs columnNameForIndex:i];
                //进行数据库列名到model之间的映射转换，拿到属性名
                NSString *propertyName;

                if(mapping) {
                    propertyName = mapping[columnName];
                    if (propertyName == nil) {
                        //如果映射未定义，则视为相同
                        propertyName = columnName;
                    }
                } else {
                    propertyName = columnName;
                }

                objc_property_t objProperty = class_getProperty(modelClass, propertyName.UTF8String);
                //如果属性不存在，则不操作
                if (objProperty) {
                    if(![rs columnIndexIsNull:i]) {
                        [self setProperty:model value:rs columnName:columnName propertyName:propertyName property:objProperty];
                    }
                }

                NSAssert(![propertyName isEqualToString:@"description"], @"description为自带方法，不能对description进行赋值，请使用其他属性名或请ColumnPropertyMappingDelegate进行映射");
            }

            //执行自定义操作
            if (block) {
                block(model, rs);
            }
            [models addObject:model];
        }

        [rs close];
    }];
    return models;
}

/**
 *  进行属性赋值
 */
- (void)setProperty:(id)model value:(FMResultSet *)rs columnName:(NSString *)columnName propertyName:(NSString *)propertyName property:(objc_property_t)property
{
    //    @"f":@"float",
    //    @"i":@"int",
    //    @"d":@"double",
    //    @"l":@"long",
    //    @"c":@"BOOL",
    //    @"s":@"short",
    //    @"q":@"long",
    //    @"I":@"NSInteger",
    //    @"Q":@"NSUInteger",
    //    @"B":@"BOOL",

    NSString *firstType = [[[[NSString stringWithUTF8String:property_getAttributes(property)] componentsSeparatedByString:@","] firstObject] substringFromIndex:];

    if ([firstType isEqualToString:@"f"]) {
        NSNumber *number = [rs objectForColumnName:columnName];
        [model setValue:@(number.floatValue) forKey:propertyName];

    } else if([firstType isEqualToString:@"i"]){
        NSNumber *number = [rs objectForColumnName:columnName];
        [model setValue:@(number.intValue) forKey:propertyName];

    } else if([firstType isEqualToString:@"d"]){
        [model setValue:[rs objectForColumnName:columnName] forKey:propertyName];

    } else if([firstType isEqualToString:@"l"] || [firstType isEqualToString:@"q"]){
        [model setValue:[rs objectForColumnName:columnName] forKey:propertyName];

    } else if([firstType isEqualToString:@"c"] || [firstType isEqualToString:@"B"]){
        NSNumber *number = [rs objectForColumnName:columnName];
        [model setValue:@(number.boolValue) forKey:propertyName];

    } else if([firstType isEqualToString:@"s"]){
        NSNumber *number = [rs objectForColumnName:columnName];
        [model setValue:@(number.shortValue) forKey:propertyName];

    } else if([firstType isEqualToString:@"I"]){
        NSNumber *number = [rs objectForColumnName:columnName];
        [model setValue:@(number.integerValue) forKey:propertyName];

    } else if([firstType isEqualToString:@"Q"]){
        NSNumber *number = [rs objectForColumnName:columnName];
        [model setValue:@(number.unsignedIntegerValue) forKey:propertyName];

    } else if([firstType isEqualToString:@"@\"NSData\""]){
        NSData *value = [rs dataForColumn:columnName];
        [model setValue:value forKey:propertyName];

    } else if([firstType isEqualToString:@"@\"NSDate\""]){
        NSDate *value = [rs dateForColumn:columnName];
        [model setValue:value forKey:propertyName];

    } else if([firstType isEqualToString:@"@\"NSString\""]){
        NSString *value = [rs stringForColumn:columnName];
        [model setValue:value forKey:propertyName];

    } else {
        [model setValue:[rs objectForColumnName:columnName] forKey:propertyName];
    }
}

相关链接：

iOS学习笔记（十六）——数据库操作(使用FMDB)