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1、/*createtables(snchar(20),snochar(8),sexchar(2)check(sex='男'orsex='女'),ageintcheck(age>=18andage<=25))createtablec(snochar(20)primarykey,cnchar(20)unique,cnochar(10)notnull,scoreintcheck(score>=0andscore<=100))altertablesadddeptchar(20)altertablesaddsnocharprimarykey?selectsn,snofr
2、omsselect*fromsselectsn,2010-agefromsselectsnas姓名,2010-ageas出生年份fromsselectdistinctdeptfromsselectsno,scorefromcwherecno='1002'selectsno,cno,scorefromcwherescore>=85selectsno,cno,scorefromcwherescore<85selectsn,dept,agefromswhereage>=19andage<=23selectsn,dept,agefromswherebetween19
3、and23?selectsn,dept,agefromswhereage<18orage>23selectsn,sexfromswheredeptin('a','b')selectsn,sexfromswheredept='a'ordept='b'select*fromswheresnlike'张%'select*fromswheresnlike'_四'createtablesc(snochar(8),cnochar(10),snchar(20),cnchar(20),scoreint)selectsno,cno,cn,scorefromcwhere(cno
4、='1001'orcno='1002')andscore>=80selectcnoas学号,count(sno)as选课人数fromcgroupbycnoselectsno,cn,cnofromcwhere(cno='1001'orcno='1002')andscore>=80orderbycnodescselect*fromcorderbysno,scoredesc？selecttop5scorefromcorderbyscoredescselect*fromcorderbysn,scoredesc*/
