Question

我无法使此代码生效，我在SQL（ WHILE ）查询中向datagridview添加行，但在执行此操作时，我需要运行foreach在里面检查是否存在 row.Cells [0] .Value ，然后再添加它，但我收到以下错误：

错误1 foreach语句无法对类型为＆＃39; System.Windows.Forms.DataGridView＆＃39;的变量进行操作。因为＆＃39; System.Windows.Forms.DataGridView＆＃39;不包含＆＃39; GetEnumerator＆＃39;的公开定义C：\用户................ project1.cs

错误2名为＆＃39; row＆＃39;的局部变量不能在此范围内声明，因为它会给“行”提供不同的含义，这已经在“父母”或“当前”中使用过。范围表示别的东西C：\ Users ................ project1.cs

这是我的代码：

//dgData is a datagridview with columns created programmatically, this works already by the way.
dgData.ColumnCount = 3; 
dgData.Columns[0].Name = "ColumnA";      
dgData.Columns[0].Name = "ColumnB"; 
dgData.Columns[0].Name = "ColumnC";

string query1 = " SELECT * FROM ....... ";


SqlCommand cmd1 = new SqlCommand(query1, connection);
            //Create a data reader and Execute the command
            SqlDataReader dataReader1 = cmd1.ExecuteReader();



Application.DoEvents();
while (dataReader1.Read())
{

    string[] row = new string[] { dataReader1["columnA"].ToString(),     dataReader1["columnB"].ToString(), dataReader1["columnC"].ToString() };
    Boolean found = false;

    // this foreach is what doesn't work.
    foreach (DataGridViewRow row in dgData)
    {
         if (row.Cells[0].Value == dataReader1["columnA"].ToString())
         {
                 // row exists
                 found = true;
                 MessageBox.Show("Row already exists");                     
         }
    }

    if (!found)
    {
         dgData.Rows.Add(row);
    }


}

Answer 1

row是string[]和循环变量的名称。重命名其中一个

DataGridView dgData不可枚举，在dgData.Rows

中迭代foreach

while (dataReader1.Read())
{
    string[] newRow = new string[] 
    { 
      dataReader1["columnA"].ToString(),
      dataReader1["columnB"].ToString(), 
      dataReader1["columnC"].ToString() 
    };
    Boolean found = false;
    foreach (DataGridViewRow row in dgData.Rows)
    {
         if (row.Cells[0].Value == dataReader1["columnA"].ToString())
         {
              // row exists
              found = true;
              MessageBox.Show("Row already exists");
              break;                   
         }
    }

    if (!found)
    {
         dgData.Rows.Add(newRow);
    }
}

如果在将行添加到datagridview

1 个答案: