DataView RowFilter Syntax [C#]

RowFilter语法

        private void btnEnquiry_Click(object sender, EventArgs e)
        {
            string filterExpression = string.Empty;
            //filter QCPass
            if (cbbQCPass.SelectedIndex != 0 && cbbQCPass.SelectedIndex != -1)
            {
                string qcPassRowFilter = string.Format("qcpass = {0}", cbbQCPass.SelectedItem);
                filterExpression += qcPassRowFilter;
            }
            //filter epc
            if (!string.IsNullOrWhiteSpace(txtEPC.Text))
            {
                if (!string.IsNullOrEmpty(filterExpression))
                {
                    filterExpression += " AND ";
                }
                string epcFilter = string.Format("epc like '%{0}%'", txtEPC.Text.Trim());
                filterExpression += epcFilter;
            }
            //filter seq
            if (!string.IsNullOrWhiteSpace(txtSEQ.Text))
            {
                if (!string.IsNullOrEmpty(filterExpression))
                {
                    filterExpression += " AND ";
                }
                string seqFilter = string.Format("seq like '%{0}%'", txtSEQ.Text.Trim());
                filterExpression += seqFilter;
            }

            if (!string.IsNullOrEmpty(filterExpression))
            {
                _dataSource.DefaultView.RowFilter = filterExpression;
            }
            else
            {
                _dataSource.DefaultView.RowFilter = string.Empty;
            }
        }