警告:我找不到名为'rowid'的列

Question

我在iOS项目中使用FMDB.但是当我用FMDB读取ROWID时,Xcode日志"警告:我找不到名为'rowid'的列."

...
 //Create database
 NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *dbPath = [documentsPath   stringByAppendingPathComponent:@"bookmarksDatabase.sqlite"];

    BOOL needCreateTable = ![[NSFileManager defaultManager] fileExistsAtPath:dbPath];
    FMDatabase *db = [FMDatabase databaseWithPath:dbPath];
    [db open];
    if (needCreateTable) {

        [db executeUpdate:@"CREATE TABLE bookmarks (title TEXT ,url TEXT ,folderID INTEGER ,locationIndex INTEGER)"];
    }
    else
    {
        [self reloadBookmarkDatabase:db];

    }

        [db close];

   ...
   //Read database. Only "ROWID" column can't find.
FMResultSet *results = [db executeQuery:@"SELECT * FROM bookmarks ORDER BY locationIndex"];
    while([results next]) {
        BookmarkData *temp  = [[BookmarkData alloc] initWithID:[results intForColumn:@"ROWID"] title:[results stringForColumn:@"title"] url:[results stringForColumn:@"url"] folderID:[results intForColumn:@"folderID"] locationIndex:[results intForColumn:@"locationIndex"]];
        [self.bookmarkArray addObject:temp];

        NSLog(@"bookmark id:%d, title:%@, url:%@, folderID:%d, locationIndex:%d",temp.ID,temp.title,temp.url,temp.folderID,temp.locationIndex);
    }

Answer 1

SELECT * 仅返回表定义中的列.

如果要获取rowid列,则必须明确列出:

SELECT *, rowid FROM ...

如果您确实需要使用此列,那么最好将其作为表定义的一部分:

CREATE TABLE bookmarks (
    ID INTEGER PRIMARY KEY,    -- same as rowid
    title TEXT,
    ...
)