将datetimepicker中的日期与数据库中的日期进行比较 [英] Compare date from datetimepicker with date from database

问题描述

//How can i do to when i select one date < or = (select u_replica from e_industrial.dbo.e1) from this query, if true show date, if > dont show.


 private void btn_search_Click(object sender, EventArgs e)
        {
            
            SqlConnection conn = new SqlConnection("Data Source=....;Initial Catalog=Innux;Persist Security Info=True;");
            conn.Open();
            SqlDataAdapter SDA = new SqlDataAdapter("select dbo.Alteracoes.Data, dbo.Funcionarios.numero as no, dbo.Funcionarios.nome, DATEPART(hour, Falta) AS faltas, DATEPART(hour, Coluna2) AS  horasextra  from dbo.Alteracoes inner join dbo.Funcionarios on dbo.Alteracoes.IDFuncionario = dbo.Funcionarios.IDFuncionario inner join dbo.Departamentos on dbo.Funcionarios.IDDepartamento = dbo.Departamentos.IDDepartamento WHERE Data = '" + dateTimePicker1.Value.ToString("yyyy/MM/dd") + "'", conn);
            DataSet dt = new DataSet();
            



            SDA.Fill(dt, "dbo.Alteracoes.Data");
            dataGridView1.DataSource = dt.Tables["dbo.Alteracoes.Data"];
            conn.Close();
        }

        private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
        {

            //dateTimePicker1.MaxDate = DateTime.Now;
            SqlConnection conn = new SqlConnection("Data Source=.....;Initial Catalog=Innux;Persist Security Info=True;");
            conn.Open();
            SqlDataAdapter pickerMaxDate = new SqlDataAdapter("select u_replica from e_industrial.dbo.e1 ('"+  dateTimePicker1.Value.ToString("yyyy/MM/dd")+"')" , conn);

            String pickerMaxDateString = pickerMaxDate.ToString();
            DateTime dtMax = Convert.ToDateTime(pickerMaxDateString);

            dateTimePicker1.MaxDate = dtMax;

            
            conn.Close();
        }

我的尝试：

What I have tried:

private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
      {

          //dateTimePicker1.MaxDate = DateTime.Now;
          SqlConnection conn = new SqlConnection("Data Source=.....;Initial Catalog=Innux;Persist Security Info=True;");
          conn.Open();
          SqlDataAdapter pickerMaxDate = new SqlDataAdapter("select u_replica from e_industrial.dbo.e1 ('"+  dateTimePicker1.Value.ToString("yyyy/MM/dd")+"')" , conn);

          String pickerMaxDateString = pickerMaxDate.ToString();
          DateTime dtMax = Convert.ToDateTime(pickerMaxDateString);

          dateTimePicker1.MaxDate = dtMax;


          conn.Close();
      }

推荐答案

停止将DateTime值转换为字符串 - 并停止通过连接将字符串传递给SQL。 br />


一旦日期采用DateTime格式，请将其保留在那里，并通过参数将其作为DateTime值传递给SQL（正如您应该将所有值传递给数据库一样） ）。然后让SQL在DATE，DATETIME或DATETIME2列中进行操作。

当您检索它时，它会以DateTime值的形式返回，并且可以直接比较。



或者它可以，如果你的SELECT语句有效......

它应该是

Stop converting DateTime values to strings - and stop passing strings to SQL by concatenation.

Once a date is in DateTime format, keep it there, and pass it to SQL as a DateTime value via parameters (as you should for all values to pass to a database). Then let SQL stroe it in a DATE, DATETIME, or DATETIME2 column.
When you retrieve it, it comes back as a DateTime value and can be compared directly.

Or it could, if your SELECT statement was valid...
It should be

SELECT columnlist FROM MyTableName WHERE TheColumnIWantToCompare = ValueToCompareItWith

你错过了WHERE和专栏。



但严肃地说，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：

You are missing the WHERE and the column.

But in all seriousness, 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？

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?

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