无法投类型的对象System.Data.SqlClient.SqlDataReader为键入'System.IConvertible“ [英] Unable to cast object of type 'System.Data.SqlClient.SqlDataReader' to type 'System.IConvertible'

问题描述

您好我一直有同样的错误作为标题说。我不知道为什么，什么是错的。我还是新来这个话，我真的不知道如何解决这个问题。如果有人可以帮助我，我会AP preciate它，如果可能的话，请给我提供需要更换一些codeS需要。谢谢你。

---

 公开数据表getAllLoanInfoDT（）
{
    使用（SqlConnection的康恩=新的SqlConnection（CONNSTRING））
    {
        的SqlCommand CMD2 =新的SqlCommand（）;
        cmd2.Connection =康恩;
        // cmd.CommandType = CommandType.StoredProcedure;
        cmd2.CommandText =SELECT DISTINCT loanUpdateDate FROM LoanPortfolio WHERE（CUSTID LIKE'OH00002'）和（loanType LIKE'个人贷款'）;
        cmd2.Parameters.AddWithValue（@ CUSTID，OH00002）;
        cmd2.Parameters.AddWithValue（@ loanType，个人贷款）;
        conn.Open（）;
        SqlDataReader的myReader = cmd2.ExecuteReader（）;
        日期时间loanUpdateDate = Convert.ToDateTime（myReader）;
        日期时间currDateTime = DateTime.Now;        INT loanToBeAdded =（（（currDateTime.Year  -  loanUpdateDate.Year）* 12）+ currDateTime.Month  -  loanUpdateDate.Month）* 500;
        如果（loanToBeAdded大于0）
        {
            串的SQL =UPDATE LoanPortfolio SET loanPaid = loanPaid ++ loanToBeAdded.ToString（）+，loanUpdateDate =+ DateTime.Now.ToString（）;
            SQL + =WHERE（loanType LIKE'个人贷款'）和（CUSTID LIKE'OH00002'）;            //此处执行上面的查询
        }
        conn.Close（）;        使用（SqlDataAdapter的爸爸=新的SqlDataAdapter（SELECT * FROM LoanPortfolio CUSTID哪里像'OH00002'，康涅狄格州））
        {
            数据表dTable =新的DataTable（）;
            dAd.Fill（dTable）;
            返回dTable;
        }
    }
}
 

解决方案

A SqlDataReader的是用来读取你的数据 - 你不能只是将它传递到Convert.ToDateTime并希望最好的结果。

首先，你会叫 myReader.Read（），并检查它返回true（也就是你有一行数据）。

然后，你会叫 Convert.ToDateTime（myReader [0]）来获得的第一个字段出来的数据读取器，并将其转换为日期。

Hi I've been having the same error as the title says. I don't know why what's wrong. I'm still new to this so, I'm not really sure how to solve this. If anyone can help me, I would appreciate it and if possible please provide me some codes that needs to be replaced. Thank you.

---

public DataTable getAllLoanInfoDT()
{ 
    using (SqlConnection conn = new SqlConnection(connString))
    {
        SqlCommand cmd2 = new SqlCommand();
        cmd2.Connection = conn;
        // cmd.CommandType = CommandType.StoredProcedure;
        cmd2.CommandText = "SELECT DISTINCT loanUpdateDate FROM LoanPortfolio WHERE (custID LIKE 'OH00002') AND (loanType LIKE 'Personal Loan')"; 
        cmd2.Parameters.AddWithValue("@custID", "OH00002");
        cmd2.Parameters.AddWithValue("@loanType", "Personal Loan");
        conn.Open();
        SqlDataReader myReader = cmd2.ExecuteReader();
        DateTime loanUpdateDate = Convert.ToDateTime(myReader);
        DateTime currDateTime = DateTime.Now;

        int loanToBeAdded = (((currDateTime.Year - loanUpdateDate.Year) * 12) + currDateTime.Month - loanUpdateDate.Month) * 500;
        if (loanToBeAdded > 0)
        {
            String sql = "UPDATE LoanPortfolio SET loanPaid = loanPaid + " + loanToBeAdded.ToString() + ", loanUpdateDate = " + DateTime.Now.ToString();
            sql += " WHERE (loanType LIKE 'Personal Loan') AND (custID LIKE 'OH00002')";

            //Execute the above query here
        }
        conn.Close();

        using (SqlDataAdapter dAd = new SqlDataAdapter("SELECT * FROM LoanPortfolio where custID like 'OH00002'", conn))
        {
            DataTable dTable = new DataTable();
            dAd.Fill(dTable);
            return dTable;
        }
    }
}

解决方案

A SqlDataReader is used to read your data - you can't just pass it into Convert.ToDateTime and hope for the best.

First you would call myReader.Read() and check it returns true (i.e. you have a row of data).

Then you would call Convert.ToDateTime(myReader[0]) to get the first field out of the data reader and convert it to a date.

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