如何将DataTable列中的空单元格替换为上述单元格的值

// 假设DataTable的变量名为dataTable
for (int rowIndex = 0; rowIndex < dataTable.Rows.Count; rowIndex++)
{
    DataRow row = dataTable.Rows[rowIndex];
    for (int columnIndex = 0; columnIndex < dataTable.Columns.Count; columnIndex++)
    {
        DataColumn column = dataTable.Columns[columnIndex];
        if (row.IsNull(column))
        {
            string columnName = column.ColumnName;
            string replacementValue = GetReplacementValue(dataTable, rowIndex, columnName);
            row[columnName] = replacementValue;
        }
    }
}

// 获取同一列的其他非空单元格的值
private string GetReplacementValue(DataTable dataTable, int rowIndex, string columnName)
{
    string replacementValue = null;
    for (int i = 0; i < dataTable.Rows.Count; i++)
    {
        DataRow row = dataTable.Rows[i];
        if (!row.IsNull(columnName))
        {
            replacementValue = row[columnName].ToString();
            break;
        }
    }
    return replacementValue;
}