如何验证在文本框中输入的日期 [英] How to validate date entered in a textbox

问题描述

我在asp.net屏幕上有一个文本框。我要求用户输入必须是今天或大于今天的日期。请让我知道该怎么做。



我尝试过：

i have a textbox on a asp.net screen. i am asking user to enter date that must be today or greater than today. please let me know how to do.

What I have tried:

SqlConnection con = new SqlConnection();
        con.ConnectionString = "Data Source=.\\sqlexpress;Initial Catalog=college_education;User ID=sa;Password=system;";
        con.Open();
        string q = "update cart set status='CO',Order_Date='" + TextBox7.Text + "',Order_Due_Date='" + TextBox1.Text + "' Where user_name='" + Session["user"] + "' and status='ATC'";
        
        SqlCommand com = new SqlCommand(q,con);
        com.ExecuteNonQuery();
        {
            Response.Write("<script>alert('Your Order is Placed Successfully. Our Agent will contact you shortly.')</script>");
        }

推荐答案

对于初学者，不要做那样的数据库！永远不要连接字符串来构建SQL命令。它让您对意外或故意的SQL注入攻击持开放态度，这可能会破坏您的整个数据库。改为使用参数化查询。



连接字符串时会导致问题，因为SQL会收到如下命令：

For starters, don't do databases like that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

就SQL而言，用户添加的引号会终止字符串，并且您会遇到问题。但情况可能更糟。如果我来并改为输入：x'; DROP TABLE MyTable; - 然后SQL收到一个非常不同的命令：

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

哪个SQL看作三个单独的命令：

Which SQL sees as three separate commands:

SELECT * FROM MyTable WHERE StreetAddress = 'x';

完全有效的SELECT

A perfectly valid SELECT

DROP TABLE MyTable;

完全有效的删除表格通讯和

A perfectly valid "delete the table" command

--'

其他一切都是评论。

所以它确实：选择任何匹配的行，从数据库中删除表，并忽略其他任何内容。



所以总是使用参数化查询！或者准备好经常从备份中恢复数据库。你定期做备份，不是吗？



检查日期相当简单：使用DateTime.TryParse将输入的字符串转换为DateTime值，如果是是有效的，将其与当前日期进行比较：

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

Checking dates is fairly easy: use DateTime.TryParse to convert the entered string into a DateTime value, then if it is valid, compare it against the current date:

DateTime dt;
if (!DateTime.TryParse(TextBox1.text, out dt))
   {
   /// Report bad date format to user...
   return;
   }
if (dt >= DateTime.Now.Date())
   {
   // Report bad date to user...
   return;
   }

然后通过参数化查询将DateTime值发送给SQL。

Then send the DateTime value to SQL via a parameterized query.

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