根据日期字段错误过滤 table

Question

我使用此代码按日期字段过滤 table（在 table 中）这是我的代码：

public double Mounthcost()
    {
        DateTime today = DateTime.Now;
        PersianCalendar persianCalendar = new PersianCalendar();
        int yearPersian = persianCalendar.GetYear(today);
        int monthPersian = persianCalendar.GetMonth(today);
        DateTime firstDayOfMonth = persianCalendar.ToDateTime(yearPersian, monthPersian, 1, 0, 0, 0, 0);
        int daysInMonth = persianCalendar.GetDaysInMonth(yearPersian, monthPersian);
        DateTime lastDayOfMonth = firstDayOfMonth.AddDays(daysInMonth - 1);
        //try
        //{
            SqlDataReader DR = ExecuteReader(System.Data.CommandType.Text, "Select Sum(Price) From Tbl_Cost Where Dat Between" + firstDayOfMonth + "AND" + lastDayOfMonth);
            if (DR.Read())
            {
                Mouth_Cost = Double.Parse(DR[0].ToString());
            }
            return Mouth_Cost;
        //}
        //catch
        //{
        //    return 0;
        //}
    }

这个错误：

An expression of non-boolean type specified in a context where a condition is expected, near 'between10'.

Answer 1

您在 SQL 查询中缺少空格

SqlDataReader DR = ExecuteReader(System.Data.CommandType.Text, "Select Sum(Price) From Tbl_Cost Where Dat Between " + firstDayOfMonth + " AND " + lastDayOfMonth);

注意 BETWEEN 和 AND 之后的空格。

Answer 2

谢谢 HABO :) 使用这个：

SqlDataReader DR = ExecuteReader(System.Data.CommandType.Text, "Select Sum(Price) From Tbl_Cost Where Dat Between @F AND @L", new SqlParameter[]
            {
                new SqlParameter("@F", firstDayOfMonth),
                new SqlParameter("@L", lastDayOfMonth),
            }

是对的...

根据日期字段错误过滤 table

Error filter the table based on a date field

c#

tsql

filter

sqldatareader