更新SQLITE查询FMDB - 初学者

Question

我可以从我的SQLITE数据库中读取数据，但无法更新它。我想知道数据库是否可写。

当我将SQL复制到SQL控制台时，代码执行成功。所以SQL没有问题。

-(BOOL) updateScores{ 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"uniques.sqlite"]; 

    FMDatabase* db = [FMDatabase databaseWithPath:writableDBPath]; 
    BOOL success; 

    if ([db open]) { 

     if ([db hadError]) { 
      NSLog(@"DB Error %d: %@", [db lastErrorCode], [db lastErrorMessage]); 
     } 

     success = [db executeUpdate:[NSString stringWithFormat:@"UPDATE Score SET answer='11' WHERE name LIKE 'jack'"]]; 

     if (success) { 
      NSLog(@"OK"); 
     }else { 
      NSLog(@"FAIL"); 
     } 

     [db close]; 
    }else { 
     NSLog(@"Problem with DB"); 
    } 

    return success; 
} 

Answer 1

总是将参数作为对象类型传递给SQL查询，请查看参数传递给SQL查询的方式。即使你传递一个数字，把它作为

[NSNumber numberWithInt:someValue] 

试试这个：

-(BOOL) updateScores 
{ 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"uniques.sqlite"]; 

    FMDatabase* db = [FMDatabase databaseWithPath:writableDBPath]; 
    BOOL success = NO; 

    if ([db open] != YES) { 
     NSLog(@"DB Error %d: %@", [db lastErrorCode], [db lastErrorMessage]); 
     return NO; //VERY IMPORTANT 
    } 

    [db beginTransaction]; 
    success = [db executeUpdate:@"UPDATE scores SET answer = ? WHERE name like ?", @"1", @"jack"]; 

    if (success) { 
     NSLog(@"OK"); 
     [db commit]; 
     [db close]; 
    }else { 
     NSLog(@"FAIL"); 
    } 

    return success; 
}