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需要帮助减去数据库列中的值(need help minus value from database column)

我试图从文本框中减去数据库列中的值我得到错误在预期条件的上下文中指定的非布尔类型的表达式

  cn.Open();
  SqlCommand command = new SqlCommand();
  command.Connection = cn;

  command.CommandText = "select * from class where  quanitity - '"+Convert.ToInt32(textBox10.Text)+"'";
  command.ExecuteNonQuery();

  cn.Close();

I am trying to minus value in database column from textbox I got error an expression of non-boolean type specified in a context where condition is expected

  cn.Open();
  SqlCommand command = new SqlCommand();
  command.Connection = cn;

  command.CommandText = "select * from class where  quanitity - '"+Convert.ToInt32(textBox10.Text)+"'";
  command.ExecuteNonQuery();

  cn.Close();

原文:https://stackoverflow.com/questions/31064964
更新时间:2020-03-26 12:16

最满意答案

你不是列的负值。你想要这样

        command.CommandText = "update class set quanitity = quanitity - "+Convert.ToInt32(textBox10.Text) ;

You are not minus value to column.you want like this

        command.CommandText = "update class set quanitity = quanitity - "+Convert.ToInt32(textBox10.Text) ;
2015-06-26

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