Tree-structuredindexingtechniquessupportbothrangeselectionsandequalityselections. ISAM:staticstructure;earlyindextechnology. B+tree:dynamic,adjustsgracefullyunderinsertsanddeletes. RangeSearches ``Findallstudentswithgpa>3.0’’ Ifdataisinsortedfile,dobinarysearchtofindfirstsuchstudent,thenscantofindothers. ...