将变量与SQLite值进行比较

Question

我需要检查是否已在我的SQLite数据库中插入变量以更改图像按钮，我尝试使用此方法但它无法正常工作：

sqlite3_stmt    *statement;
const char *dbpath = [databasePath UTF8String];

if (sqlite3_open(dbpath, &Preferiti) == SQLITE_OK)
{
    NSString *checkSQL = [NSString stringWithFormat: @"SELECT * FROM ListaEventi WHERE idEvento=%@", [DettagliEvento objectAtIndex:7]];

    const char *insert_stmt = [checkSQL UTF8String];

    sqlite3_prepare_v2(Preferiti, insert_stmt, -1, &statement, NULL);

    if (sqlite3_step(statement) == SQLITE_DONE)
    {
        [_preferito setImage:[UIImage imageNamed:@"staroff.png"] forState:UIControlStateNormal];
        _preferito.tag=0;

    } else {
        [_preferito setImage:[UIImage imageNamed:@"staron.png"] forState:UIControlStateNormal];
        _preferito.tag=1;
    }

    sqlite3_finalize(statement);
    sqlite3_close(Preferiti);
}

有没有其他方法可以编写语句来将变量与我的SQLite表中的值进行比较？