Question

我在下面的while循环中收到错误，表示＆＃34;无法隐式转换类型＆＃39; float＆＃39;到＆＃39;字符串＆＃39;＆＃34;。

try
{    
    string ab = "select Sum(amount) from matriculationfee ";
    SqlCommand myCommand = new SqlCommand(ab, con);
    SqlDataReader myReader;

    con.Open();
    myReader = myCommand.ExecuteReader();

    while (myReader.Read())
    {          
        txtbalance.Text=(((float)myReader["amount"]).ToString());
        //It Says here that it Cannot Implicity convert type 'float' to 'string
    }
}

catch (SqlException w)
{
    MessageBox.Show("Erro!" + w.Message);
}

请帮助我。

Answer 1

首先，您需要命名要返回的列：

string ab = "select Sum(amount) AS amount from matriculationfee ";

然后我建议您简化转换代码：

var amount = float.Parse(myReader["amount"]);
txtbalance.Text= amount.ToString();

Answer 2

将结果总和如下：

string ab = "select SUM(amount) AS total from matriculationfee ";

然后像这样参考：

var amount = myReader.GetFloat("total");
txtbalance.Text= amount.ToString();

获得SUM（）的价值

2 个答案: