FMDB初步使用小结

　　频繁的网络请求会给用户不好的体验，在最近开发的一个项目中有一个获取个人详细信息的界面，由于是子页面，进入页面后需要重新加载数据并刷新页面，而，每一次请求服务器再返回数据不仅用户体验不好，也花费手机流量，所以尝试使用一下FMDB。简单看了下别人的博客和官方DEMO，自己尝试将FMDB加入到项目里面去。

　　创建DB：

-(NSString *)dbPath
{
    static NSString *_path;
    if (_path) {
        return _path;
    }
　　//获取程序路径
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);
    NSString *documentDirectory = [paths objectAtIndex:0];
    NSString *dbPath = [documentDirectory stringByAppendingString:@"MSProduct.db"];
    _path = dbPath;
    return  _path;
}

    NSString *dbPath = [self dbPath];
　　//根据路径创建一个数据库对象
    FMDatabase *db = [FMDatabase databaseWithPath:dbPath];
    return db;

　　创建Table：

      
    NSString SQL = @"CREATE TABLE IF NOT EXISTS tableName (uid integer,name text,photo text)";
    FMDatabase *db = [self createDB];
    if ([db open]) {
        return [db executeUpdate:SQL];
    }

　　字段类型，text，integer，blob，当然其他的我也不清楚，也没去研究。项目里面目前用到了text和integer。 db的executeUpdate方法就是执行SQL语句，其实不只创建Table用到这个方法，删除数据，添加，修改等都可以使用这个方法，查看FMDB源代码可以看到还有其他“重载”方法

- (BOOL)executeUpdate:(NSString*)sql withArgumentsInArray:(NSArray *)arguments;

- (BOOL)executeUpdate:(NSString*)sql values:(NSArray *)values error:(NSError * __autoreleasing *)error;

- (BOOL)executeUpdate:(NSString*)sql withParameterDictionary:(NSDictionary *)arguments;

- (BOOL)executeUpdate:(NSString*)sql withVAList: (va_list)args;

　　其实只要掌握了SQL语句的使用，那么掌握FMDB的基本功能还不算太难。像删除语句：DELETE FROM TABLE WHERE 1=1 修改语句：UPDATE TABLE SET NAME = 'newname' WHERE 1=1

　　最后还有一个查询，查询结果都放在 FMResultSet 中，它有一个 next 方法，循环遍历每一行（row）数据。示例代码：

    NSString *querySQL =[NSString stringWithFormat:@"SELECT * FROM %@ WHERE cvnumber=%ld",kMSTableNameUserInfo,cvnumber];
    FMResultSet *result = [[MSDataBase sharedMSDataBase] queryData:querySQL]; //FMResultSet *result = [db executeQuery:SQL];

    MSUserCard *user = [[MSUserCard alloc] init];
    while ([result next]) {
        user.cvnumber = [result intForColumn:@"cvnumber"];
        user.name = [result stringForColumn:@"name"];
        user.headphoto = [result stringForColumn:@"headphotos"];
        user.company = [result stringForColumn:@"company"];
        user.email = [result stringForColumn:@"email"];
        user.mobile = [result stringForColumn:@"mobile"];
        user.position = [result stringForColumn:@"position"];
        user.landline = [result stringForColumn:@"landline"];
        user.weixin = [result stringForColumn:@"weixin"];
        user.address = [result stringForColumn:@"address"];
        user.ability = [result stringForColumn:@"ability"];
        user.achieve = [result stringForColumn:@"achieve"];
        user.identitytitle = [result stringForColumn:@"identitytitle"];
        user.hidemobile = [result intForColumn:@"hidemobile"];
    }

上述例子是获取单条数据的。当然多条同样适用，只要读取出来，剩下的随便操作了。FMResultSet其他方法

- (int)columnCount;

- (int)columnIndexForName:(NSString*)columnName;

- (NSString*)columnNameForIndex:(int)columnIdx;

- (int)intForColumn:(NSString*)columnName;

- (int)intForColumnIndex:(int)columnIdx;

- (long)longForColumn:(NSString*)columnName;

- (long)longForColumnIndex:(int)columnIdx;

- (long long int)longLongIntForColumn:(NSString*)columnName;

- (long long int)longLongIntForColumnIndex:(int)columnIdx;

- (unsigned long long int)unsignedLongLongIntForColumn:(NSString*)columnName;

- (unsigned long long int)unsignedLongLongIntForColumnIndex:(int)columnIdx;

- (BOOL)boolForColumn:(NSString*)columnName;

- (BOOL)boolForColumnIndex:(int)columnIdx;

- (double)doubleForColumn:(NSString*)columnName;

- (double)doubleForColumnIndex:(int)columnIdx;

- (NSString*)stringForColumn:(NSString*)columnName;

- (NSString*)stringForColumnIndex:(int)columnIdx;


- (NSDate*)dateForColumn:(NSString*)columnName;


- (NSDate*)dateForColumnIndex:(int)columnIdx;



- (NSData*)dataForColumn:(NSString*)columnName;


- (NSData*)dataForColumnIndex:(int)columnIdx;


- (const unsigned char *)UTF8StringForColumnName:(NSString*)columnName;


- (const unsigned char *)UTF8StringForColumnIndex:(int)columnIdx;


- (id)objectForColumnName:(NSString*)columnName;

- (id)objectForColumnIndex:(int)columnIdx;