Question

我正在尝试保留一张记录表，以查看玩家输给其他玩家的次数，但在记录栏中，这些数字会被减去。

我的输出：

Name          Won    Lost    Record
-----------------------------------
Player 1       4      3        1

Player 2       3      4       -1

期望的输出：

Name          Won    Lost    Record
-----------------------------------
Player 1       4      3        4-3

Player 2       3      4        3-4

以下是我给出的输出代码：

            string columnBeat1 = "[BEAT " + tbl1_p2Txt.Text.ToUpper() + "]";
            string columnBeat2 = "[BEAT " + tbl1_p1Txt.Text.ToUpper() + "]";
            string columnLost1 = "[LOST TO " + tbl1_p2Txt.Text.ToUpper() + "]";
            string columnLost2 = "[LOST TO " + tbl1_p1Txt.Text.ToUpper() + "]";
            string columnRecordBeat = "[RECORD VS " + tbl1_p2Txt.Text.ToUpper() + "]";
            string columnRecordLost = "[RECORD VS " + tbl1_p1Txt.Text.ToUpper() + "]";

            SqlCommand cmdBeat = new SqlCommand("UPDATE dbo.[RECORD] SET " + columnBeat1 + " = " + columnBeat1 + " + 1 " + " WHERE [NAME] = @Name", con);
            SqlCommand cmdLost = new SqlCommand("UPDATE dbo.[RECORD] SET " + columnLost2 + " = " + columnLost2 + " + 1 " + " WHERE [NAME] = @Name", con);
            SqlCommand cmdRecordBeat = new SqlCommand("UPDATE dbo.[RECORD] SET " + columnRecordBeat + " = " + columnBeat1 + '-' + columnLost1 + " WHERE [NAME] = @Name", con);
            SqlCommand cmdRecordLost = new SqlCommand("UPDATE dbo.[RECORD] SET " + columnRecordLost + " = " + columnBeat2 + '-' + columnLost2 + " WHERE [NAME] = @Name", con);

            cmdBeat.CommandType = CommandType.Text;
            cmdLost.CommandType = CommandType.Text;
            cmdRecordBeat.CommandType = CommandType.Text;
            cmdRecordLost.CommandType = CommandType.Text;

            con.Open();
            cmdBeat.Parameters.AddWithValue("@Name", tbl1_p1Txt.Text);
            cmdBeat.ExecuteNonQuery();
            cmdLost.Parameters.AddWithValue("@Name", tbl1_p2Txt.Text);
            cmdLost.ExecuteNonQuery();
            cmdRecordBeat.Parameters.AddWithValue("@Name", tbl1_p1Txt.Text);
            cmdRecordBeat.ExecuteNonQuery();
            cmdRecordLost.Parameters.AddWithValue("@Name", tbl1_p2Txt.Text);
            cmdRecordLost.ExecuteNonQuery();
            con.Close();

Answer 1

因为输入不是字符串。使用单引号或使用sqlparameter

设置它

Answer 2

正如@FrankX在他的回答中所述，问题在于你处理的是数字，而不是字符串。在两个数字之间加一个减号通常意味着你要减去 - 这里的SQL不是例外。

让我们首先考虑如何在C＃中执行此操作。

int winCount = GetWinCount();   // get the value 4 from somewhere, e.g. the database
int lossCount = GetLostCount(); // get the value 3 from somewhere, e.g. the database

string resultColumnName = "Result";
string winsColumnName = "Wins";     // we don't actually need this
string lossesColumnName = "Losses"; // we don't actually need this

// what we want is a string like this:
// Result='4-3'

string query = "UPDATE ... SET " + resultColumnName + " = '" + winCount + "-" + lossCount + "' WHERE ..."

现在，C＃实际上隐藏了我们感兴趣的部分：winCount和lossCount是int s，但我们需要string s。这发生在幕后。构建查询的行中的+以静默方式将这两个值分别转换为字符串“4”和“3”。

如果我们不想在C＃中这样做，我们需要告诉数据库创建一个'X-Y'形式的字符串值，其中X和Y是转换为字符串的整数。我暂时没有在SQL中做过这种事情，所以我不能告诉你确切的语法，而是寻找CONVERT和CONCAT函数。

在构建查询字符串的C＃中，您需要将winsColumnName，lossesColumnName与这些函数结合使用。从C＃的角度来看，函数名称当然只是字符串。它看起来与此类似：

string query = "... " + resultColumnName + "=CONCAT(CONVERT(VARCHAR, " + winsColumnName + "), '-', CONVERT(VARCHAR, " + lossesColumnName + ")) ..."

Answer 3

这是SQL Server。尝试这样的事情：

        SqlCommand cmdRecordBeat = new SqlCommand("UPDATE dbo.[RECORD] SET " + columnRecordBeat + " = " + CAST(columnBeat1 AS VARCHAR) + '-' + CAST(columnLost1 AS VARCHAR) + " WHERE [NAME] = @Name", con);
        SqlCommand cmdRecordLost = new SqlCommand("UPDATE dbo.[RECORD] SET " + columnRecordLost + " = " + CAST(columnBeat2 AS VARCHAR) + '-' + CAST(columnLost2 AS VARCHAR) + " WHERE [NAME] = @Name", con);

希望它对你有所帮助。

为什么输出字符串中的数字会被减去？

3 个答案: