-----内联结3个表返回产品的折扣信息-----SELECT p.Name,s.DiscountPct from Sales.SpecialOffer sinner JOIN Sales.SpecialOfferProduct o ONs.SpecialOfferID=o.SpecialOfferIDINNER JOIN Production.Product p ONo.ProductID=p.ProductIDWHERE p.Name ='All-Purpose Bike Stand'-----外联结2个表返回税率状态、省-----SELECT s.CountryRegionCode,s.StateProvinceCode,t.TaxType,t.TaxRate FROM Person.StateProvince sLEFT OUTER JOIN Sales.SalesTaxRate t ONs.StateProvinceID=t.StateProvinceID-----比较内联结-----SELECT s.CountryRegionCode,s.StateProvinceCode,t.TaxType,t.TaxRate FROM Person.StateProvince sINNER JOIN Sales.SalesTaxRate t ONs.StateProvinceID=t.StateProvinceID-----交叉联结-----SELECT s.CountryRegionCode,s.StateProvinceCode,t.TaxType,t.TaxRate FROM Person.StateProvince sCROSS JOIN Sales.SalesTaxRate t-----实现自联结-----SELECT e.EmployeeID,e.Title,m.Title AS ManagerTitlefrom HumanResources.Employee eLEFT OUTER JOIN HumanResources.Employee m ONe.ManagerID = m.EmployeeID-----使用衍生表------SELECT DISTINCT s.PurchaseOrderNumberFROM Sales.SalesOrderHeader sINNER JOIN (SELECT SalesOrderIDFROM Sales.SalesOrderDetailWHERE UnitPrice BETWEEN 1000 AND 2000) d ONs.SalesOrderID=d.SalesOrderID-----使用 UNION 组合结果集-----SELECT SalesPersonID,GETDATE() QuotaDate,SalesQuotaFROM Sales.SalesPersonWHERE SalesQuota>0UNION SELECT SalesPersonID,QuotaDate,SalesQuotaFROM Sales.SalesPersonQuotaHistoryWHERE SalesQuota>0ORDER BY SalesPersonID DESC,QuotaDate DESC