linq等于SQL LIKE子句的数据集

Question

What is the linq equivalent of a SQL clause like WHERE UserName LIKE 'fr_d' ?

I'm working with a dataset in memory rather than a SQL database so I don't think I can use something like where SqlMethods.Like(p.UserName, "Fr_d")

(Not that my installation of VS2008 is admitting that SqlMethods or even System.Data.Linq.SqlClient exist at the moment, but thats a whole different problem!)

Answer 1

Like this:

table.Where(row => row.StringColumn.StartsWith("prefix"))

(You may also want to call Contains or EndsWith )

EDIT : In your case, you want

table.Where(p => p.UserName.StartsWith("Fr") && p.UserName.EndsWith("d") && p.UserName.Length == 4)

Alternatively, you can also put a regex inside the Where clause.
If you do, make sure to create the RegEx object outside the Where call so that it doesn't get parsed for each row.

Answer 2

I belive this is what you really want. It will allow Fr{ any one character }d:

table.Where(p => p.UserName.StartsWith("Fr") && p.UserName.EndsWith("d") && p.UserName.Length == 4 )

Unfortunately I can't find anything that does something similar to SQL's like clause for LINQ to Dataset...

UPDATE: Found a similar posting here: LINQ vs. DataTable.Select - How can I get the same results?

They suggest using i4o which I am not familiar with, but it may be worth investigating (the asker of that question accepted i4o as the answer).