Question

我在C＃中有一个字符串，其中包含一个表的列名，如下所示

shown_itemsName = "billno,department,date,subtotal,tea,coffee";

我想在dataGridView中显示一个表，其中包含字符串中的列名（shown_itemsName），但是当我编写sql查询时

cmdDataBase.CommandText = "select @shown_itemsName from employee.transaction where department = @department AND MONTH(date) = @month_ AND YEAR(date) = @year_";
cmdDataBase.Parameters.AddWithValue("@shown_itemsName", shown_itemsName);
cmdDataBase.Parameters.AddWithValue("@department", this.department.Text);
cmdDataBase.Parameters.AddWithValue("@month_", this.dateTimePicker1.Value.Month);
cmdDataBase.Parameters.AddWithValue("@year_", this.dateTimePicker1.Value.Year);

我得到的表只有1列和4行，单元格值为billno，department，date，subtotal，tea，coffee，该列的标题也是相同的字符串。而我应该得到6列和4行作为结果与“，”分隔的子串作为列名

Answer 1

您无法添加带参数的新列。如果它是动态的，你不能选择，而是每次都编写查询并在其上执行CommandType.Text命令。

对于每个请求，您必须：

cmdDataBase.CommandText = "select " + shown_itemsName + " from employee.transaction where department = @department AND MONTH(date) = @month_ AND YEAR(date) = @year_";

cmdDataBase.Parameters.AddWithValue("@department", this.department.Text);
cmdDataBase.Parameters.AddWithValue("@month_", this.dateTimePicker1.Value.Month);
cmdDataBase.Parameters.AddWithValue("@year_", this.dateTimePicker1.Value.Year);

using(var reader = cmdDataBase.ExecuteReader()) {
    while(reader.Read()) {
        // ...
    }
    reader.Close();
}

带有动态列名的C＃中的mysql select命令

1 个答案: