Describe your issue

when you use in a query function like !string.IsNullOrEmpty it is converted to SQL like
SELECT
Count(*)
FROM
[Data$t11] [auto968]
WHERE
NOT ([auto968].[text] IS NULL OR Len([auto968].[text]) = 0)

and according to [https://learn.microsoft.com/en-us/sql/t-sql/functions/len-transact-sql?view=sql-server-ver16] LEN Returns the number of characters of the specified string expression, excluding trailing spaces. It means that string of space characters will not match the predicate. Please use DATALEN or fix it in a different proper way.

Steps to reproduce

GetTable().Where (_=> !string.IsNullOrEmpty(_.text)).Count()

Environment details

Linq To DB version: 4.3.0

Database (with version): SQL Server 2019

ADO.NET Provider (with version): Microsoft.Data.SqlClient 4.1.0

Operating system: Windows 10

.NET Version: net4.8