部分依赖: if →>β,ya,y→B B部分依赖于α CTO(CNO, TNAME, ADDRESS, OFFICE) CNO→ TNAME, TNAME→> ADDRESS partial dependency (CNO, TNAME)→ ADDRESS▪ if: → , , → 部分依赖于 . CTO(CNO,TNAME,ADDRESS,OFFICE): CNO→TNAME,TNAME→ ADDRESS partial dependency: (CNO, TNAME)→ADDRESS 部分依赖: