LINQ to Entities using the SQL LIKE operator

问题

I have this:

query = query.Where(s => s.ShowTypeDescription == showTypeDescription);

several times for different variables in order to build dynamic SQL.

How would I go about transforming the above to say:

query = query.Where(s => s.ShowTypeDescription **LIKE** showTypeDescription);

?

回答1:

If all you want is to find a substring within another string, the best way to do this is with the Contains method:

query = query.Where(s => s.ShowTypeDescription.Contains(showTypeDescription));

Because the String.Contains method translates to:

CHARINDEX(ShowTypeDescription, @showTypeDescription) > 0

Which is roughly equivalent to:

ShowTypeDescription LIKE '%' + @showTypeDescription + '%'

Update: In Linq-to-SQL, you can use the SqlMethods.Like method:

query = query.Where(s => SqlMethods.Like(s.ShowTypeDescription, showTypeDescription));

This will directly translate to the SQL LIKE operator. Note, however, this won't work outside of Linq-to-SQL queries. Trying to call this method in other contexts will throw an exception.

回答2:

query = query.Where(s => s.ShowTypeDescription.Contains(showTypeDescription));

   Contains() is translated LIKE '%term%'
   StartsWith() = LIKE 'term%'
   EndsWith()   = LIKE '%term'

来源：https://stackoverflow.com/questions/17097764/linq-to-entities-using-the-sql-like-operator