我如何在 linq 中使用 2 个条件

Question

my code not answer

var SabteGheybat = from row in db.InfoStudents.Where(p => p.PayeTahsili == comboBox1.SelectedItem.ToString()
                && p.Gheybat != Mydate)

                               select row;

Answer 1

If there is an error please provide error information to everyone.
If your query has no error message then it looks like you forget lazy query.
please use ToList() because your query is legal.

var SabteGheybat = (from row in db.InfoStudents.Where(p => p.PayeTahsili == comboBox1.SelectedItem.ToString()
                && p.Gheybat != Mydate)
    select row).ToList();

i try the same logic and it's result:

and you can simplify query like:

var SabteGheybat = db.InfoStudents.Where(p => p.PayeTahsili == comboBox1.SelectedItem.ToString()
                && p.Gheybat != Mydate)

Answer 2

if you are getting error you need change your code like this:

var con = comboBox1.SelectedItem.ToString()
var SabteGheybat = from row in db.InfoStudents.Where(p => p.PayeTahsili == con
        && p.Gheybat != Mydate)

OR use this format:

var con = comboBox1.SelectedItem.ToString()
var SabteGheybat =  db.InfoStudents.Where(p => p.PayeTahsili == con
        && p.Gheybat != Mydate).toList()