SQL-LINQ-Lambda语法对照

SQL

LINQ

Lambda

SELECT *FROM Employee

from e in Employees select e

 Employees .Select (e => e)

 SELECT LoginID,JobTitle FROM Employee

from e in Employees select new {e.LoginID, e.JobTitle}

 Employees.Select (
      e => new {
            LoginID = e.LoginID, 
            JobTitle = e.JobTitle
         }
   )

 SELECT LoginID AS ID, JobTitle AS Title FROM Employee

from e in Employees

select new {ID = e.LoginID, Title = e.JobTitle}

 Employees.Select (
      e => new 
         {
            ID = e.LoginID, 
            Title = e.JobTitle
         }
   )

 SELECT DISTINCT JobTitle FROM Employee 

(from e in Employees select e.JobTitle).Distinct()

Employees
   .Select (e => e.JobTitle)
   .Distinct ()

 SELECT e.*

FROM HumanResources.Employee AS e

WHERE e.LoginID = 'test'

 from e in Employees

where e.LoginID == "test"

select e

 Employees
   .Where (e => (e.LoginID == "test"))

 SELECT e.*

FROM HumanResources.Employee AS e

WHERE e.LoginID = 'test' AND e.SalariedFlag = 1

 from e in Employees

where e.LoginID == "test" && e.SalariedFlag

select e

 Employees
   .Where (e => ((e.LoginID == "test") && e.SalariedFlag))

 SELECT e.* FROM HumanResources.Employee AS e

WHERE e.VacationHours >= 2 AND e.VacationHours <= 10

 from e in Employees

where e.VacationHours >= 2 && e.VacationHours <= 10

select e

 Employees
   .Where (e => (((Int32)(e.VacationHours) >= 2) && ((Int32)(e.VacationHours) <= 10)))

 SELECT e.* FROM HumanResources.Employee AS e
ORDER BY e.NationalIDNumber

 from e in Employees

orderby e.NationalIDNumber

select e

 Employees
   .OrderBy (e => e.NationalIDNumber)

 SELECT e.* FROM HumanResources.Employee AS e

ORDER BY e.HireDate DESC, e.NationalIDNumber

 from e in Employees

orderby e.HireDate descending, e.NationalIDNumber

select e

 Employees
   .OrderByDescending (e => e.HireDate)
   .ThenBy (e => e.NationalIDNumber)

 SELECT e.* FROM HumanResources.Employee AS e

WHERE e.JobTitle LIKE 'Vice%' OR SUBSTRING(e.JobTitle, 0, 3) = 'Pro'

 from e in Employees

where e.JobTitle.StartsWith("Vice") || e.JobTitle.Substring(0, 3) == "Pro"

select e

 Employees
   .Where (e => (e.JobTitle.StartsWith ("Vice") || (e.JobTitle.Substring (0, 3) == "Pro")))

 SELECT SUM(e.VacationHours)

FROM HumanResources.Employee AS e

 Employees.Sum(e => e.VacationHours);

 SELECT COUNT(*) FROM HumanResources.Employee AS e

 Employees.Count();

 SELECT SUM(e.VacationHours) AS TotalVacations, e.JobTitle

FROM HumanResources.Employee AS e

GROUP BY e.JobTitle

 from e in Employees

group e by e.JobTitle into g

select new {JobTitle = g.Key, TotalVacations = g.Sum(e => e.VacationHours)}

 Employees
   .GroupBy (e => e.JobTitle)
   .Select (
      g => new 
         {
            JobTitle = g.Key, 
            TotalVacations = g.Sum (e => (Int32)(e.VacationHours))
         }
   )

 SELECT e.JobTitle, SUM(e.VacationHours) AS TotalVacations

FROM HumanResources.Employee AS e

GROUP BY e.JobTitle

HAVING e.COUNT(*) > 2

 from e in Employees

group e by e.JobTitle into g

where g.Count() > 2

select new {JobTitle = g.Key, TotalVacations = g.Sum(e => e.VacationHours)}

 Employees
   .GroupBy (e => e.JobTitle)
   .Where (g => (g.Count () > 2))
   .Select (
      g => 
         new 
         {
            JobTitle = g.Key, 
            TotalVacations = g.Sum (e => (Int32)(e.VacationHours))
         }
   )

 SELECT *

FROM Production.Product AS p, Production.ProductReview AS pr

 from p in Products

from pr in ProductReviews

select new {p, pr}

 Products
   .SelectMany (
      p => ProductReviews, 
      (p, pr) => 
         new 
         {
            p = p, 
            pr = pr
         }
   )

 SELECT *

FROM Production.Product AS p

INNER JOIN Production.ProductReview AS pr ON p.ProductID = pr.ProductID

 from p in Products

join pr in ProductReviews on p.ProductID equals pr.ProductID

select new {p, pr}

 Products
   .Join (
      ProductReviews, 
      p => p.ProductID, 
      pr => pr.ProductID, 
      (p, pr) => 
         new 
         {
            p = p, 
            pr = pr
         }
   )

SELECT *
FROM Product AS p INNER JOIN ProductCostHistory AS c 
　　ON p.ProductID = c.ProductID AND 
　　　　p.SellStartDate = c.StartDate

from p in Products
join pch in ProductCostHistories on 
new {p.ProductID, StartDate = p.SellStartDate} 
　　equals new {pch.ProductID, StartDate = pch.StartDate}
select new {p, pch}

Products.Join (ProductCostHistories,
p =>new {ProductID = p.ProductID, StartDate = p.SellStartDate}, 
pch =>new {ProductID = pch.ProductID,StartDate = pch.StartDate }, 
(p, pch) =>  new {p = p, pch = pch}
)

 SELECT *

FROM Production.Product AS p

LEFT OUTER JOIN Production.ProductReview AS pr ON p.ProductID = pr.ProductID

 from p in Products

join pr in ProductReviews on p.ProductID equals pr.ProductID

into prodrev

select new {p, prodrev}

 Products
   .GroupJoin (
      ProductReviews, 
      p => p.ProductID, 
      pr => pr.ProductID, 
      (p, prodrev) => 
         new 
         {
            p = p, 
            prodrev = prodrev
         }
   )

 SELECT p.ProductID AS ID

FROM Production.Product AS p

UNION

SELECT pr.ProductReviewID

FROM Production.ProductReview AS pr

 (from p in Products

select new {ID = p.ProductID}).Union(

from pr in ProductReviews

select new {ID = pr.ProductReviewID})

 Products
   .Select (
      p => 
         new 
         {
            ID = p.ProductID
         }
   )
   .Union (
      ProductReviews
         .Select (
            pr => 
               new 
               {
                  ID = pr.ProductReviewID
               }
         )
   )

 SELECT TOP (10) *

FROM Production.Product AS p

WHERE p.StandardCost < 100

 (from p in Products

where p.StandardCost < 100

select p).Take(10)

 Products
   .Where (p => (p.StandardCost < 100))
   .Take (10)

 SELECT *

FROM [Production].[Product] AS p

WHERE p.ProductID IN(

    SELECT pr.ProductID

    FROM [Production].[ProductReview] AS [pr]

    WHERE pr.[Rating] = 5

    )

 from p in Products

where (from pr in ProductReviews

where pr.Rating == 5

select pr.ProductID).Contains(p.ProductID)

select p

 Products
   .Where (
      p => 
         ProductReviews
            .Where (pr => (pr.Rating == 5))
            .Select (pr => pr.ProductID)
            .Contains (p.ProductID)
   )