DataTable搜索表达式

Question

我遇到了从DataTable.search获取结果的挑战。我正在使用的表达式没有得到结果。表达式的长度是否有限制？那可以用吗？使用DataTable中的所有列是错误的吗？

我正在尝试比较两个具有相同定义的DataTable中的行。使用第一个，我尝试获取不在第二个中的行并将它们保存在＆＃39; ResultDataTable＆＃39;以便使用保存值更新第一个DataTable的DataBase。

private DataTable ExtractRecord(DataTable localTable, DataTable importedTable)
{
    DataTable returnTable = new DataTable(importedTable.TableName);

    DataRow[] returnedDataRows;
    Dictionary<int, string> DicColumnDataType = new Dictionary<int, string>();
    for (int i = 0; i < importedTable.Columns.Count; i++)
    {
        DicColumnDataType.Add(i, importedTable.Columns[i].DataType.Name);
        myDataColumn newCol = new myDataColumn(importedTable.Columns[i].ColumnName.ToString(), importedTable.Columns[i].DataType);
        returnTable.Columns.Add(newCol);
        returnTable.AcceptChanges();
    }
    foreach (DataRow row in importedTable.Rows)
    {
        object[] RowValues = row.ItemArray;

        string Expression = "WHERE " + @" ";

        int ColCount = localTable.Columns.Count;
        for (int i = 0; i < ColCount; i++)
        {
            switch (DicColumnDataType[i])
            {
                case "Int32":
                    Expression = Expression.Remove(Expression.Length - 1, 1);
                    Expression += importedTable.Columns[i].ColumnName + " Like '%" + RowValues[i] + "%' AND " + " ";
                    break;
                case "String":
                    Expression = Expression.Remove(Expression.Length - 1, 1);
                    Expression += importedTable.Columns[i].ColumnName + " Like '%" + RowValues[i] + "%' AND " + " ";
                    break;
                case "Boolean":
                    Expression = Expression.Remove(Expression.Length - 1, 1);
                    Expression += importedTable.Columns[i].ColumnName + " Like '% " + RowValues[i] + "%' AND " + " ";
                    break;
                case "DateTime":
                    Expression = Expression.Remove(Expression.Length - 1, 1);
                    Expression += importedTable.Columns[i].ColumnName + " Like '%#" + RowValues[i] + "#%' AND " + " ";
                    break;

            }
        }

        Expression = Expression.Substring(0, Expression.Length - 6);

        try
        {
            returnedDataRows = localTable.Select(Expression);

            if (1 > returnedDataRows.Length)
            {
                returnTable.ImportRow(row);
                returnedDataRows = null;
            }
        }
        catch
        {

        }

    }

    returnTable.AcceptChanges();
    return returnTable;
}