使用BETWEEN运算符的SQL查询导致"查询表达式中的数字语法错误"

Question

我正在使用MS Access数据库.我想获得2个日期之间的第一个和最后一个记录.但是在使用BETWEEN运算符时出错:

查询表达式'Datum_k BETWEEN 3.4.2017中的语法错误数.和3.4.2017.'.

我的代码:

private void GetPrviZadnjiBrojRacuna()
{
    OleDbCommand commandOD = new OleDbCommand("SELECT Dokument FROM DnevniPromet WHERE (Datum_k BETWEEN " + datumOd + " AND " + datumDo + ") ORDER BY [Datum_k] ASC", dataModel.CS);
    OleDbCommand commandDO = new OleDbCommand("SELECT Dokument FROM DnevniPromet WHERE [Datum_k] >= " + datumOd + " AND [Datum_k] <= " + datumDo + " ORDER BY [Datum_k] DESC", dataModel.CS);

    try
    {
        dataModel.DT.Clear();
        OleDbDataAdapter ODbDA = new OleDbDataAdapter(commandOD);

        if (!dataModel.CS.State.Equals(ConnectionState.Open))
        {
            dataModel.CS.Open();
        }

        // GET OD 
        ODbDA.Fill(dataModel.DT);
        odRacuna = dataModel.DT.Rows[0].ToString();

        // GET DO
        ODbDA.SelectCommand = commandDO; 
        dataModel.DT.Clear();
        ODbDA.Fill(dataModel.DT);

        doRacuna = dataModel.DT.Rows[0].ToString();

        dataModel.CS.Close();
        dataModel.DataLoaded = true;
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.ToString());
    }
}

Answer 1

解决代码段中的两个问题:

• 您永远不应该使用字符串插值来构建查询.这有助于SQL注入.关于这一点的许多主题很多.我建议你读一读.
• 您错过了'日期字符串周围的单引号.

使用参数化查询,您可以一举两得:

OleDbCommand commandOD = new OleDbCommand(@"
    SELECT Dokument
    FROM DnevniPromet
    WHERE (Datum_k BETWEEN @datumOd AND @datumDo)
    ORDER BY [Datum_k] ASC", dataModel.CS);

commandOD.Parameters.AddRange(new OleDbParameter[]
{
    new OleDbParameter("@datumOd", datumOd),
    new OleDbParameter("@datumDo", datumDo)
});