sqlite異常沒有這樣的列

Question

以下方法，應該檢查記錄是否已經存在於表中或者沒有。但是，我收到語法錯誤沒有這樣的列。

public void ifExist(int myId) 
{ 
    string dbPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "ormdemo.db3"); 
    var db = new SQLiteConnection(dbPath); 
    SQLiteCommand cmd = new SQLiteCommand(db); 
    cmd.CommandText = "SELECT count(*) FROM storeConsumption WHERE Id = ?"+ myId; 

    int count = Convert.ToInt32(cmd.ExecuteScalar<storeConsumption>()); 
    if (count == 0) 
    { 
     Console.WriteLine("The record is NOT Existed");  
    } 
    else 
    { 
     Console.WriteLine("The record is Existed"); 
    } 
}  

我也試着像這樣運行：

cmd.CommandText = "SELECT count(*) FROM storeConsumption WHERE Id= ?'"+ myId+"'"; 

雖然，仍然有同樣的錯誤。如果你有一個想法，我該如何解決它，我會感激不盡。

} 

Answer 1

它似乎是由「Id =？」引起的。請嘗試使用以下命令行來添加參數

cmd.CommandText =「SELECT count（*）FROM storeConsumption WHERE Id = @myId」; cmd.Parameters.Add（「@ myId」，myId）;

更多信息： https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.commandtext(v=vs.110).aspx

Answer 2

更新：下面這段代碼已經解決了錯誤，它運作良好：

public async Task<Boolean> ifExist(int id){ 

    var result = await sdb.databaseConnection().ExecuteScalarAsync<int>("SELECT count(*) FROM storeConsumption WHERE Id = ?", id); 
    Console.WriteLine(result); 
    if (result > 0) return true; 

    return false; 

}