Len

2005
2008
2012
2014
2016
2017
2019
2022

2005, 2008, 2012, 2014, 2016, 2017, 2019, 2022

Len (Length) String Function

Use the Len function to return the number of characters in a string expression.

Syntax

db.fx.Len({expression})

Arguments

expression: – The value to determine the length of.

Returns

long or long?

(depending on the nullability of `expression`)

Microsoft SQL Server returns bigint if expression is of the varchar(max), varbinary(max), or nvarchar(max) data types; otherwise, int. dbExpression generally maps these to CLR types long and int respectively. As the dbExpression implementation for Len works with the CLR type string, there is no way to effect a different return type based on the length of the provided {expression} method parameter. Therefore, Len in dbExpression always returns long or long?.

Examples

Select Statement

Select the length of a person's last name.

IEnumerable<long> result = db.SelectMany(
		db.fx.Len(dbo.Person.LastName)
	)
	.From(dbo.Person)
	.Execute();

Where Clause

Select persons whose last name is longer than their first name.

IEnumerable<Person> persons = db.SelectMany<Person>()
	.From(dbo.Person)
	.Where(db.fx.Len(dbo.Person.LastName) > db.fx.Len(dbo.Person.FirstName))
	.Execute();

Order By Clause

Select a list of persons, ordered descending by the length of their last name.

IEnumerable<Person> result = db.SelectMany<Person>()
	.From(dbo.Person)
	.OrderBy(db.fx.Len(dbo.Person.LastName).Desc())
	.Execute();

Group By Clause

Select a list of address values grouped by address type and the length of the city field.

IEnumerable<dynamic> values = db.SelectMany(
		dbo.Address.AddressType,
		db.fx.Len(dbo.Address.City).As("city")
	)
	.From(dbo.Address)
	.GroupBy(
		dbo.Address.AddressType,
		db.fx.Len(dbo.Address.City)
	)
	.Execute();

Having Clause

Select a list of address data, grouped by address type and city where the value of city has only 1 character.

IEnumerable<dynamic> addresses = db.SelectMany(
		db.fx.Count().As("count"),
		dbo.Address.AddressType,
		dbo.Address.City
	)
	.From(dbo.Address)
	.GroupBy(
		dbo.Address.AddressType,
		dbo.Address.City
	)
	.Having(
		db.fx.Len(dbo.Address.City) == 1
	)
	.Execute();