C＃SqlCommand查詢更新

Question

我試圖找到它。但我找不到我的答案。所以我決定提出這個問題。我需要你的幫助。

我希望將值添加到表值中，而不會覆蓋Debit，Score列。它會增加當前值。

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> 

當我從textBox1的= 999，TextBox2中= 500，textBox3 = 50

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

添加值我知道這樣的SQL查詢。但我不知道如何編寫代碼SqlCommand

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

有什麼建議嗎？

（對不起，我的英語太可怕了，我希望你們明白我想問）

感謝

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); 

請注意逐字字符串@"..."語法。請不要忘記處置（明確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+ =運算符進行更新。像這樣改變你的sql命令;

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

Answer 3

這將幫助你....只是試圖以這種方式..

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();