LINQ To SQL Contains Case Sensitive Searching

Question

When I use below query, it gets result perfectly. But it is case-sensitive. Here is my codes:

    IQueryable<article> results;
    if (rrbAuthor.IsChecked)
        results = (from a in _db.articles join k in _db.keywords on a.id equals k.aid where a.author.Contains(textBox1.Text) select a).Distinct();
    else if (rrbKeywords.IsChecked)
        results = (from a in _db.articles join k in _db.keywords on a.id equals k.aid where k.word.Contains(textBox1.Text) select a).Distinct();
    else
        results = (from a in _db.articles join k in _db.keywords on a.id equals k.aid where a.title.Contains(textBox1.Text) select a).Distinct();

    ListArticles(results, 1);

How can I manage to get results in in-sensitive case?

@HabipOĞUZtry following `k.word.ToLower().Contains(textBox1.Text.ToLower())` — tchelidze, Jan 19 '16 at 12:52
@tchelidze Ok! Sorry my for my coriosity. Is it according to the rules? — , Jan 19 '16 at 12:56
Your question has already been [asked (and answered)](http://stackoverflow.com/questions/841226/case-insensitive-string-compare-in-linq-to-sql) before... — Richard Ev, Jan 19 '16 at 13:06
@tchelidze Using `ToLower()` both two side sounds plaster over the wound. — , Jan 19 '16 at 13:09
@HabipOĞUZ Ok, then you can use comparison like this `string1.Equals(string2, StringComparison.OrdinalIgnoreCase)` — tchelidze, Jan 19 '16 at 13:14

tchelidze · Accepted Answer · 2016-01-19T13:05:07.837

You can transform string into lower case, using ToLower() method and then do comparison
You can also use null propagation in oder to avoid NullReference Exception in case some of the stirngs is null.

Try following

  IQueryable<article> results;
  if (rrbAuthor.IsChecked)
    results = (from a in _db.articles join k in _db.keywords on a.id equals k.aid
               where a.author?.ToLower().Contains(textBox1.Text?.ToLower()) == true
               select a).Distinct();
  else if (rrbKeywords.IsChecked)
    results = (from a in _db.articles join k in _db.keywords on a.id equals k.aid
               where k.word?.ToLower().Contains(textBox1.Text?.ToLower()) == true
               select a).Distinct();
  else
    results = (from a in _db.articles join k in _db.keywords on a.id equals k.aid
               where a.title?.ToLower().Contains(textBox1.Text?.ToLower()) == true
               select a).Distinct();
  ListArticles(results, 1);

score 1 · Answer 2 · answered Jan 19 '16 at 12:58

You can use .ToUpper() or .ToLower() two sides:

    results = (from a in _db.articles join k in _db.keywords on a.id equals k.aid 
where a.author.ToUpper().Contains(textBox1.Text.ToUpper()) select a).Distinct();

Or

    results = (from a in _db.articles join k in _db.keywords on a.id equals k.aid 
where a.author.ToLower().Contains(textBox1.Text.ToLower()) select a).Distinct();

LINQ To SQL Contains Case Sensitive Searching

2 Answers2