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1、Chapter3:SQLChapter3:SQLDataDefinitionBasicQueryStructureSetOperationsAggregateFunctionsNullValuesNestedSubqueriesComplexQueriesViewsModificationoftheDatabaseJoinedRelations**3.1HistoryIBMSequellanguagedevelopedaspartofSystemRprojectattheIBMSanJoseResearchLaboratoryRenamedStructur
2、edQueryLanguage(SQL)ANSIandISOstandardSQL:SQL-86SQL-89SQL-92SQL:1999(languagenamebecameY2Kcompliant!)SQL:2003Commercialsystemsoffermost,ifnotall,SQL-92features,plusvaryingfeaturesetsfromlaterstandardsandspecialproprietaryfeatures.Notallexamplesheremayworkonyourparticularsystem.3.2
3、DataDefinitionLanguageTheschemaforeachrelation.Thedomainofvaluesassociatedwitheachattribute.IntegrityconstraintsThesetofindicestobemaintainedforeachrelations.Securityandauthorizationinformationforeachrelation.Thephysicalstoragestructureofeachrelationondisk.Allowsthespecificationof
4、notonlyasetofrelationsbutalsoinformationabouteachrelation,including:1.DomainTypesinSQLchar(n).Fixedlengthcharacterstring,withuser-specifiedlengthn.varchar(n).Variablelengthcharacterstrings,withuser-specifiedmaximumlengthn.Nchar(n),nVarchar(n)(forunicode,2bytecode,1-4000chars)Text.
5、Variablelengthcharacterstrings,1to2GB.=varchar(max)int.Integer(4B,afinitesubsetoftheintegersthatismachine-dependent).smallint.Smallinteger(2B,asubsetoftheintegerdomaintype).Bigint.Biginteger(8B),tinyint(1B),bit(多个位占1B)numeric(p,d).Fixedpointnumber,withuser-specifiedprecisionofpdig
6、its,withddigitstotherightofdecimalpoint.Decimal(p,d).1.DomainTypesinSQL(cnt)real,doubleprecision.Floatingpointanddouble-precisionfloatingpointnumbers,withmachine-dependentprecision.float(n).Floatingpointnumber,withuser-specifiedprecisionofatleastndigits.Datatime8B:yyyy.mm.ddh:m:s,
7、smalldatatime4BMoney8BXml(<2GB)(不同表单可以存在xml类型的属性字段中)Binary(n)1-8000BImage<2GBTimestamp8BSql_variant<8016bit，可存储除text、image、timestamp、sql-variantCursor:查询结果的数据集Table：表格式数据2.Createdatabase/tabaleCREATEDATABASEdatabase_nameONPRIMARY(NAME=student_dataFILENAME=‘C:ProgramFilesMicrosof
8、terverMSSQL.1MSSQLDatastudent
