Question

DateTime fromDate = dateTimePicker1.Value, toDate = dateTimePicker2.Value;

string query2 = "select * from Sales where DatePurchased >= '" + fromDate.ToShortDateString() + "' AND DatePurchased <='" + toDate.ToShortDateString() + "'";

using (OleDbConnection conn2 = new OleDbConnection(connStr))
{
    using (OleDbCommand command = new OleDbCommand(query2, conn2))
    {
        command.Connection = conn2;
        conn2.Open();
        OleDbDataReader reader = command.ExecuteReader();

        while (reader.Read())
        {
            graphics.DrawString(string.Format("{0:000000}", reader.GetInt32(0)), font, new SolidBrush(Color.Black), startX, startY + offset);
            graphics.DrawString(reader.GetString(1), font, new SolidBrush(Color.Black), startX+90, startY + offset);
            graphics.DrawString(reader.GetString(2), font, new SolidBrush(Color.Black), startX + 250, startY + offset);
            graphics.DrawString(Convert.ToString(reader.GetDouble(3)), font, new SolidBrush(Color.Black), startX + 500, startY + offset);

            startY += 35;
        }
    }
}

我在这里发现错误：

OleDbDataReader reader = command.ExecuteReader();

错误是

“未处理OleDbException：条件表达式中的数据类型不匹配。”

我不知道该怎么做，我在数据库中的数据是在日期/时间。请帮忙

Answer 1

您的ToShortDateString（）不是与sql兼容的字符串：

fromDate.ToString("yyyyMMdd")

将为您提供与sql兼容的日期字符串。

string query2 = "select * from Sales where DatePurchased >= '" + fromDate.ToString("yyyyMMdd")+ "' AND DatePurchased <='" + toDate.ToString("yyyyMMdd")+ "'";

然而，使用参数化查询会更好。

Answer 2

如果修复了您的错误，请尝试将查询更改为

string query2 = "select * from Sales where DatePurchased between " + fromDate.ToShortDateString() + " AND " + toDate.ToShortDateString() + " "

如果它不起作用，请检查这两个日期范围之间是否有数据。

Answer 3

试试这个：

string query2 = "select * from Sales where DatePurchased >= '" + fromDate.ToString("yyyy-MM-dd") + "' AND DatePurchased <='" + toDate.ToString("yyyy-MM-dd") + "'";

之前它适用于我

查询过滤数据库

3 个答案: