[转]LinqToSql的问题 多条件 动态变化查询条件怎样查询

//第一种方法
DataClasses3DataContext con = new DataClasses3DataContext();

var qu = from c in con.FeeMain select c;

if (textBox1.Text != "")
qu = qu.Where(c => c.wtdw == textBox1.Text);
if (textBox2.Text != "")
qu = qu.Where(c => c.vessel == textBox2.Text);

dataGridView1.DataSource = qu;

//第二种方法
DataClasses3DataContext con = new DataClasses3DataContext();
var searchPredicate1 = PredicateExtensions.True<FeeMain>();
if (textBox1.Text != "")
searchPredicate1 = searchPredicate1.And(c => c.wtdw == textBox1.Text);
if (textBox2.Text != "")
searchPredicate1 = searchPredicate1.And(c => c.vessel == textBox2.Text);

var a = from c in con.FeeMain.Where(searchPredicate1) select c;
dataGridView1.DataSource = a;