Question

从C＃代码，我试图执行一个查询并将两个参数传递给Access数据库。不幸的是，参数名称是相同的，因为我传递的是日期参数。似乎当我对代码进行了优化时，第一个参数被第二个参数替换，所以例如我正在传递

开始日期为1/1/2017，结束日期为1/31/2017

我仍然获得2016年的价值。

以下是我的代码

string ConnString = getConnstring();
        string DirectoryPath = getDirectortyPath(year, quater);
        StreamWriter file = new StreamWriter(DirectoryPath);
        string StartDate = calculateStartDate(year, quater);
        string EndDate = CalculateEndDate(year, quater);
        string SqlString = "Select * from TestTable where compl_date >= ? and compl_date <= ?";
        using (OleDbConnection conn = new OleDbConnection(ConnString))

        {

            using (OleDbCommand cmd = new OleDbCommand(SqlString, conn))

            {

                cmd.CommandType = CommandType.Text;
                cmd.Parameters.AddWithValue("compl_date", StartDate); // startDate can be 1/1/2017
                cmd.Parameters.AddWithValue("compl_date", EndDate);  // end date could be 1/31/2017
                conn.Open();

                using (OleDbDataReader reader = cmd.ExecuteReader())

                {

                    while (reader.Read())

                    {
                        try
                        {
                            string FullLine = "";

如何获取上述日期范围内的值。

Answer 1

尝试这样;

string ConnString = getConnstring();
            string DirectoryPath = getDirectortyPath(year, quater);
            StreamWriter file = new StreamWriter(DirectoryPath);
            string StartDate = calculateStartDate(year, quater);
            string EndDate = CalculateEndDate(year, quater);
            string SqlString = "Select * from TestTable where compl_date >= @StartDate and compl_date <= @EndDate";
            using (OleDbConnection conn = new OleDbConnection(ConnString))    
            {    
                using (OleDbCommand cmd = new OleDbCommand(SqlString, conn))
                {
                    cmd.CommandType = CommandType.Text;
                    cmd.Parameters.AddWithValue("@StartDate", StartDate); 
                    cmd.Parameters.AddWithValue("@EndDate", EndDate);  
                    conn.Open();
....

传递两个相同的参数来访问数据库

1 个答案: