If you are already working with SQL and are familiar with SQL queries then you may find you at time are thinking of converting SQL syntax to LINQ syntax when writing LINQ. Following cheat sheet should help you with some of the common queries

SQL | LINQ | Lambda |

SELECT * FROM HumanResources.Employee | from e in Employees select e | Employees |

SELECT e.LoginID, e.JobTitle FROM HumanResources.Employee AS e | from e in Employees select new {e.LoginID, e.JobTitle} | Employees |

SELECT e.LoginID AS ID, e.JobTitle AS Title FROM HumanResources.Employee AS e | from e in Employees select new {ID = e.LoginID, Title = e.JobTitle} | Employees |

SELECT DISTINCT e.JobTitle FROM HumanResources.Employee AS e | (from e in Employees select e.JobTitle).Distinct() | Employees |

SELECT e.* FROM HumanResources.Employee AS e WHERE e.LoginID = ‘test’ | from e in Employees where e.LoginID == "test" select e | Employees |

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 |

SELECT e.* WHERE e.VacationHours >= 2 AND e.VacationHours <= 10 | from e in Employees where e.VacationHours >= 2 && e.VacationHours <= 10 select e | Employees |

SELECT e.* FROM HumanResources.Employee AS e | from e in Employees orderby e.NationalIDNumber select e | Employees |

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 |

SELECT 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 |

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 |

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 |

SELECT * FROM Production.Product AS p, Production.ProductReview AS pr | from p in Products from pr in ProductReviews select new {p, pr} | Products |

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 |

SELECT * FROM Production.Product AS p INNER JOIN Production.ProductCostHistory AS pch ON p.ProductID = pch.ProductID AND p.SellStartDate = pch.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 |

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 |

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 TOP (10) * FROM Production.Product AS p WHERE p.StandardCost < 100 | (from p in Products where p.StandardCost < 100 select p).Take(10) | Products |

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 |