转换时，我收到此错误“将varchar转换为数据类型int时转换失败." [英] whille casting i get this error "Conversion failed when converting the varchar to data type int."

问题描述

private void comboBoxCliNo_SelectedIndexChanged(object sender, EventArgs e)
       {
           try
           {
               SqlCommand cmd = new SqlCommand("select * from client where clientId=''" + comboBoxCliNo.Text + "''" , con);
               con.Close();
               con.Open();
               SqlDataReader rdr = cmd.ExecuteReader();
               if (rdr.Read())
               {
                   lblFirstName.Text = rdr[0].ToString();
                   lblAddress.Text = rdr[1].ToString();
                   lblPhone.Text = rdr[2].ToString();
               }
               else
               {
                   lblFirstName.Text = "";
                   lblAddress.Text = "";
                   lblPhone.Text = "";
               }
               con.Close();
           }
           catch (Exception df)
           {
               MessageBox.Show(df.Message);
           }
       }

推荐答案

更改此行

SqlCommand cmd = new SqlCommand("select * from client where clientId=" + ConvertTo.Int32(comboBoxCliNo.Text) + "" , con);

您正在尝试将字符串与int进行比较.

You were trying to compare string with int.

SqlCommand cmd = new SqlCommand("select * from client where clientId=" + ConvertTo.Int32(comboBoxCliNo.Text) , con);

原因是您的clientId栏是整数.您是否正在尝试传递字符串.您也无需添加单引号.

The reason would be ur clientId column is integer. Nad you are trying to pass a string. you no need to include single quotes also.

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