C＃SqlCommand查询更新

Question

我试图找到它。但我找不到我的答案。所以我决定提出这个问题。我需要你的帮助。

我希望将值添加到表值中，而不会覆盖Debit，Score列。它会增加当前值。

cmd = new SqlCommand("UPDATE Users SET Debit=@debit, 
             Score=@score 
           WHERE Phone=@phone", con); 

con.Open(); 

cmd.Parameters.AddWithValue("@phone", textBox1.Text); 
cmd.Parameters.AddWithValue("@debit", textBox2.Text); 
cmd.Parameters.AddWithValue("@score", textBox3.Text); 

cmd.ExecuteNonQuery(); 

MessageBox.Show("Амжилттай"); 
con.Close(); 

例如：

Table, Phone: 999 | Debit: 1500 | Score: 100 //current <br> 

当我从textBox1的= 999，TextBox2中= 500，textBox3 = 50

Table, Phone: 999, Debit: 2000, Score: 150 //updating like that 

添加值我知道这样的SQL查询。但我不知道如何编写代码SqlCommand

UPDATE Users 
SET Debit = Debit + [user input], Score = Score + [user input] 
WHERE = Phone 

有什么建议吗？

（对不起，我的英语太可怕了，我希望你们明白我想问）

感谢

Answer 1

如果你想添加，只是添加：

cmd = new SqlCommand(@"UPDATE Users 
          SET Debit = Debit + @debit, 
           Score = Score + @score 
         WHERE Phone = @phone", con); 

请注意逐字字符串@"..."语法。请不要忘记处置（明确Close是反模式）：

string sql = 
    @"UPDATE Users 
     SET Debit = Debit + @debit, 
      Score = Score + @score 
    WHERE Phone = @phone"; 

//TODO: put the right connection string instead of "MyConnectionStringHere" 
//DONE: IDisposable (SqlConnection) should be wrapped into using 
using (var con = new SqlConnection("MyConnectionStringHere")) { 
    con.Open(); 

    //DONE: IDisposable (SqlCommand) should be wrapped into using 
    using (var cmd = new SqlCommand(sql, con)) { 
    //TODO: AddWithValue is often a bad choice; change to Add 
    cmd.Parameters.AddWithValue("@phone", textBox1.Text); 
    cmd.Parameters.AddWithValue("@debit", textBox2.Text); 
    cmd.Parameters.AddWithValue("@score", textBox3.Text); 

    cmd.ExecuteNonQuery(); 
    //TODO: a better policy is to read localized strings from resources 
    MessageBox.Show("Амжилттай"); 
    } 
} 

Answer 2

您可以使用+ =运算符进行更新。像这样改变你的sql命令;

UPDATE Users SET Debit+=@debit, 
       Score+=@score 
           WHERE Phone=@phone 

Answer 3

这将帮助你....只是试图以这种方式..

SqlCommand cmd = new SqlCommand("UPDATE Users SET Debit = Debit + " + textBox2.Text + ", Score = Score + " + textBox3.Text + " WHERE Phone = " + textBox1.Text + "", con); 
       con.Open(); 
       cmd.ExecuteNonQuery(); 
       MessageBox.Show("Амжилттай"); 
       con.Close(); 

OR

SqlCommand cmd = new SqlCommand("UPDATE Users SET Debit = Debit + @debit, Score = Score + @score WHERE Phone = @phone", con); 
       con.Open(); 
       cmd.Parameters.AddWithValue("@phone", textBox1.Text); 
       cmd.Parameters.AddWithValue("@debit", textBox2.Text); 
       cmd.Parameters.AddWithValue("@score", textBox3.Text); 
       cmd.ExecuteNonQuery(); 
       MessageBox.Show("Амжилттай"); 
       con.Close();