Databases Reference
In-Depth Information
verbose than a typical hand-written SQL would be, it is recognizable and easy enough to
read:
SELECT
[Extent1].[CustomerID] AS [CustomerID],
[Extent1].[CompanyName] AS [CompanyName],
[Extent1].[ContactName] AS [ContactName],
[Extent1].[ContactTitle] AS [ContactTitle],
[Extent1].[Address] AS [Address],
[Extent1].[City] AS [City],
[Extent1].[Region] AS [Region],
[Extent1].[PostalCode] AS [PostalCode],
[Extent1].[Country] AS [Country],
[Extent1].[Phone] AS [Phone],
[Extent1].[Fax] AS [Fax]
FROM [dbo].[Customers] AS [Extent1]
WHERE
N'London'
= [Extent1].[City]
ORDER BY [Extent1].[CompanyName] ASC
Notice that the literal
'London'
is embedded in this SQL statement only because it was
hard-coded in the original LINQ query. If the value comes from a method parameter or a
variable, which is normally the case when executing queries in response to user input, the
Entity Framework generates parameterized SQL statements.
string city
=
“London”;
var query = from c in context.Customers
where c.City ==
city
select c;
The modified LINQ query just shown translates into the following SQL statement where
the city is no longer embedded in the query itself and instead passed as a parameter:
SELECT
[Extent1].[CustomerID] AS [CustomerID],
[Extent1].[CompanyName] AS [CompanyName],
[Extent1].[ContactName] AS [ContactName],
[Extent1].[ContactTitle] AS [ContactTitle],
[Extent1].[Address] AS [Address],
[Extent1].[City] AS [City],
[Extent1].[Region] AS [Region],
[Extent1].[PostalCode] AS [PostalCode],
[Extent1].[Country] AS [Country],
[Extent1].[Phone] AS [Phone],
[Extent1].[Fax] AS [Fax]
FROM [dbo].[Customers] AS [Extent1]
WHERE [Extent1].[City] = @p__linq__0
