microtechpoint首席执行官创始人brian alderman mctmodule 4 grouping and aggregating dataod1Module 4分组汇DataOd1.pptx

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microtechpoint首席执行官创始人brian alderman mctmodule 4 grouping and aggregating dataod1Module 4分组汇DataOd1.pptx

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04|GroupingandAggregatingDataBrianAlderman|MCT,CEO/FounderofMicroTechPointTobiasTernstrom|MicrosoftSQLServerProgramManager

CourseTopicsQueryingMicrosoftSQLServer2012JumpStart01|IntroducingSQLServer2012 SQLServertypesofstatements;otherSQLstatementelements;basicSELECTstatements02|AdvancedSELECTStatements DISTINCT,Aliases,scalarfunctionsandCASE,usingJOINandMERGE;Filteringandsortingdata,NULLvalues03|SQLServerDataTypes Introducedatatypes,datatypeusage,convertingdatatypes,understandingSQLServerfunctiontypes04|GroupingandAggregatingData Aggregatefunctions,GROUPBYandHAVINGclauses,subqueries;self-contained,correlated,andEXISTS;Views,inline-tablevaluedfunctions,andderivedtables|LunchBreak Eat,drink,andrechargefortheafternoonsession

AggregatefunctionsGROUPBYandHAVINGclausesSubqueries(self-contained,correlated,andEXISTS)WorkingwithtablefunctionsModuleOverview

AggregateFunctions

Commonbuilt-inaggregatefunctionsSTDEVSTDEVPVARVARPSUMMINMAXAVGCOUNTCOUNT_BIGCHECKSUM_AGGGROUPINGGROUPING_IDCommonStatisticalOther

WorkingwithaggregatefunctionsAggregatefunctions:Returnascalarvalue(withnocolumnname)IgnoreNULLsexceptinCOUNT(*)CanbeusedinSELECT,HAVING,andORDERBYclausesFrequentlyusedwithGROUPBYclauseUniqueOrdersAvg_UnitPriceMin_OrderQtyMax_LineTotal--------------------------------------------------31465465.0934127893.619000SELECTCOUNT(DISTINCTSalesOrderID)ASUniqueOrders,AVG(UnitPrice)ASAvg_UnitPrice,MIN(OrderQty)ASMin_OrderQty,MAX(LineTotal)ASMax_LineTotalFROMSales.SalesOrderDetail;

UsingDISTINCTwithaggregatefunctionsUseDISTINCTwithaggregatefunctionstosummarizeonlyuniquevaluesDISTINCTaggregateseliminateduplicatevalues,notrows(unlikeSELECTDISTINCT)Compare(withpartialresults):SELECTSalesPersonID,YEAR(OrderDate)ASOrderYear,COUNT(CustomerID)ASAll_Cust