数据类型问题

Question

我正在尝试使用此字段将新记录插入表中，但是它给了我“条件表达式中的数据类型不匹配......我已经检查了类型，它总是会失败...

我不知道该字段的大小是否正确，需要帮助吗？

    public static void InsertCommand(Veicolo v, string connString)
    {
        using (OleDbConnection connection = new OleDbConnection(connString))
        {
            connection.Open();
            OleDbCommand cmd = new OleDbCommand
            {
                CommandText = "INSERT INTO Veicoli VALUES ('@targa', @automoto,'@marca', '@modello', @cilindrata, @potenzakw," +
                "@immatricolazione,@usato,@kmzero,@kmpercorsi,'@colore',@prezzo,'@imagepath','@caratteristica');",
                Connection=connection
            };
            cmd.Parameters.Add("@targa",OleDbType.VarChar,255).Value= v.Targa;
            cmd.Parameters.Add("@automoto",OleDbType.Boolean,2).Value = (v is Auto);
            cmd.Parameters.Add("@marca", OleDbType.VarChar, 255).Value = v.Marca;
            cmd.Parameters.Add("@modello", OleDbType.VarChar, 255).Value = v.Modello;
            cmd.Parameters.Add("@cilindrata", OleDbType.Integer, 32).Value = v.Cilindrata;
            cmd.Parameters.Add("@potenzakw", OleDbType.Double, 32).Value = v.PotenzaKw;
            cmd.Parameters.Add("@immatricolazione", OleDbType.DBDate, 32).Value = v.Immatricolazione;
            cmd.Parameters.Add("@usato", OleDbType.Boolean, 2).Value = v.IsUsato;
            cmd.Parameters.Add("@kmzero", OleDbType.Boolean, 2).Value = v.IsKmZero;
            cmd.Parameters.Add("@kmpercorsi", OleDbType.Integer, 32).Value = v.KmPercorsi; 
            cmd.Parameters.Add("@colore", OleDbType.VarChar, 255).Value = v.Colore;
            cmd.Parameters.Add("@prezzo", OleDbType.Double, 32).Value = v.Prezzo;
            cmd.Parameters.Add("@imagepath", OleDbType.VarChar, 255 ).Value = v.ImagePath;
            string c = (v is Auto ? (v as Auto).NumeroAirBag.ToString() : (v as Moto).MarcaSella);
            cmd.Parameters.Add("@caratteristica", OleDbType.VarChar, 255).Value =c;
            cmd.Prepare();
            cmd.ExecuteNonQuery();    //ERROR data type mismatch in criteria expression
        }
    }

    public static string createTableVeicoliSqlString =
        $"CREATE TABLE Veicoli (" +
            $"Targa varchar(255) NOT NULL PRIMARY KEY," +
            $"AutoMoto boolean," +
            $"Marca varchar(255)," +
            $"Modello varchar(255)," +
            $"Cilindrata int," +
            $"PotenzaKw double," +
            $"Immatricolazione datetime," +
            $"Usato boolean," +
            $"KmZero boolean," +
            $"KmPercorsi int," +
            $"Colore varchar(255)," +
            $"Prezzo double," +
            $"ImagePath varchar(255)," +
            $"Caratteristica varchar(255)" +
            $");";

Answer 1

除了您排除的原因外，可能有多种原因：

1. “ Veicolo v”中的一个属性为空，并且db字段不可为空。
2. 您的插入脚本错过了代码中没有的另一个不可为空的字段。