System.DateTime Methods (LINQ to SQL)

The following LINQ to SQL-supported methods, operators, and properties are available to use in LINQ to SQL queries. When a method, operator or property is unsupported, LINQ to SQL cannot translate the member for execution on the SQL Server. You may use these members in your code, however, they must be evaluated before the query is translated to Transact-SQL or after the results have been retrieved from the database.

Supported System.DateTime Members

Once mapped in the object model or external mapping file, LINQ to SQL allows you to call the following System.DateTime members inside LINQ to SQL queries.

Supported DateTime Methods	Supported DateTime Operators	Supported DateTime Properties
Add	Addition	Date
AddDays	Equality	Day
AddHours	GreaterThan	DayOfWeek
AddMilliseconds	GreaterThanOrEqual	DayOfYear
AddMinutes	Inequality	Hour
AddMonths	LessThan	Millisecond
AddSeconds	LessThanOrEqual	Minute
AddTicks	Subtraction	Month
AddYears		Now
Compare		Second
CompareTo(DateTime)		TimeOfDay
Equals(DateTime)		Today
		Year

Members Not Supported by LINQ to SQL

The following members are not supported inside LINQ to SQL queries.

IsDaylightSavingTime	IsLeapYear
DaysInMonth	ToBinary
ToFileTime	ToFileTimeUtc
ToLongDateString	ToLongTimeString
ToOADate	ToShortDateString
ToShortTimeString	ToUniversalTime
FromBinary	UtcNow
FromFileTime	FromFileTimeUtc
FromOADate	GetDateTimeFormats

Method Translation Example

All methods supported by LINQ to SQL are translated to Transact-SQL before they are sent to SQL Server. For example, consider the following pattern.

(dateTime1 – dateTime2).{Days, Hours, Milliseconds, Minutes, Months, Seconds, Years}

When it is recognized, it is translated into a direct call to the SQL Server DATEDIFF function, as follows:

DATEDIFF({DatePart}, @dateTime1, @dateTime2)

SQLMethods Date and Time Methods

In addition to the methods offered by the DateTime structure, LINQ to SQL offers the methods listed in the following table from the System.Data.Linq.SqlClient.SqlMethods class for working with date and time.

DateDiffDay	DateDiffMillisecond	DateDiffNanosecond
DateDiffHour	DateDiffMinute	DateDiffSecond
DateDiffMicrosecond	DateDiffMonth	DateDiffYear

See Also

Reference

SQL-CLR Type Mapping (LINQ to SQL)

Other Resources

Query Concepts in LINQ to SQL

Creating the Object Model (LINQ to SQL)

Data Types and Functions (LINQ to SQL)