最近在做一個(gè)項(xiàng)目需要用到持久性存儲(chǔ)，在Core Data以及FMDB中選擇用哪個(gè)比較好，最后使用了FMDB，主要是因?yàn)樗呀?jīng)將SQLite都封裝好了，使用起來比較簡(jiǎn)單，容易上手，不得不說老外真的很牛！??

FMDB GitHub下載地址
使用方法主要還是要看文檔。

首先當(dāng)然就是倒入FMDB文件夾到我們自己的項(xiàng)目里，這樣才能使用到它。
這里主要還是記錄一些簡(jiǎn)單的使用方法

• 創(chuàng)建數(shù)據(jù)庫(kù):

- (void)createDateBase {
    NSString *documents = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *fileName = [documents stringByAppendingPathComponent:@"user.sqlite"];
    self.db = [FMDatabase databaseWithPath:fileName];
}

文件的保存路徑就是/Documents/user.sqlite

• 建表

- (void)createTable {
    [self openDateBase];
    
    NSString *sql = @"create table UserTable(uId integer primary key autoincrement, date text, mileage integer, oilNumber text, money float, oilPrice float, litre double, percentage integer, place text, other text);";
    BOOL b = [self.db executeUpdate:sql];
    if (b) {
        NSLog(@"創(chuàng)建表成功");
    }else {
        NSLog(@"創(chuàng)建表失敗");
    }
    
    [self closeDateBase];
}

FMDB中打開關(guān)閉的方法是
[self.db open];
[self.db close];
這里我自己寫了打開和關(guān)閉數(shù)據(jù)庫(kù)的方法，主要是加了一個(gè)判斷：

- (void)openDateBase {
    if (self.db != nil) {
        [self.db open];
    }
}

- (void)closeDateBase {
    if (self.db != nil) {
        [self.db close];
    }
}

• 保存數(shù)據(jù)到數(shù)據(jù)庫(kù)
  這里用到了簡(jiǎn)單的SQL語句

- (void)saveUserData {
    [self openDateBase];
    BOOL b = [self.db executeUpdate:@"insert into UserTable (date, mileage, oilNumber, money, oilPrice, litre, percentage, place, other) values (?, ?, ?, ?, ?, ?, ?, ?, ?);", _userDate, [NSNumber numberWithInteger:_userMileage], _userOilNumber, [NSNumber numberWithFloat:_userMoney], [NSNumber numberWithFloat:_userOilPrice], [NSNumber numberWithFloat:_userLitre], [NSNumber numberWithInteger:_userPercentage], _userPlace, _userOther];
    
    if (b) {
        NSLog(@"保存成功");
    }else {
        NSLog(@"保存失敗");
    }
    [self closeDateBase];
}

• 當(dāng)然還有查詢，F(xiàn)MDB中提供了一個(gè)[r next]的遍歷方法，只要存在下一個(gè)數(shù)據(jù)就會(huì)繼續(xù)

- (void)queryData {
    NSString *sql = @"select uId, date, mileage, oilNumber, money, oilPrice, litre, percentage, place, other from UserTable;";
    [self openDateBase];
    FMResultSet *r = [self.db executeQuery:sql];
    _allDatas = [[NSMutableArray alloc] init];
    
    while ([r next]) {
        _userId = [r intForColumn:@"uId"];
        _userDate = [r stringForColumn:@"date"];
        _userMileage = [r intForColumn:@"mileage"];
        _userOilNumber = [r stringForColumn:@"oilNumber"];
        _userMoney = [r longForColumn:@"money"];
        _userOilPrice = [r longForColumn:@"oilPrice"];
        _userLitre = [r longForColumn:@"litre"];
        _userPercentage = [r intForColumn:@"percentage"];
        _userPlace = [r stringForColumn:@"place"];
        _userOther = [r stringForColumn:@"other"];
        NSLog(@"數(shù)據(jù)：%ld,%@,%ld,%@,%.2f,%.2f,%.2f,%ld,%@,%@", _userId, _userDate, _userMileage, _userOilNumber, _userMoney, _userOilPrice, _userLitre, _userPercentage, _userPlace, _userOther);

    }
    [self closeDateBase];
}

查詢中用到了FMResultSet，當(dāng)查詢成功后會(huì)返回FMResultSet值，同時(shí)FMResultSet 提供了很多方便的方法來查詢數(shù)據(jù)：

intForColumn:
longForColumn:
longLongIntForColumn:
boolForColumn:
doubleForColumn:
stringForColumn:
dateForColumn:
dataForColumn:
dataNoCopyForColumn:
UTF8StringForColumn:
objectForColumn:

我的項(xiàng)目里還用到了計(jì)算數(shù)據(jù)庫(kù)里有多少行數(shù)

//計(jì)算數(shù)據(jù)庫(kù)行數(shù)保存到_count中
- (void)countsFromDataBase {
    [self openDateBase];
    _count = [self.db intForQuery:@"select count(*) from UserTable"];
    NSLog(@"該表count = %lu", _count);
    [self closeDateBase];
}

這些都是我實(shí)際中用到的一些東西，當(dāng)然不是很全面。