ï¼1ï¼ R1产åï¼å·pkãåãè§æ ¼ãåå·ï¼ R2ä»åºï¼å·pkãåãå°åï¼ R3åæ¾ï¼ä»å·pkã产å·pkãæ°éï¼
(2) create table ä»åºW(W# char(10),WN char(10) not null,WA char(10), constraint pk_w# primary key(W#) )
(3) grant select on ä»åºW to public;
revoke select on ä»åºW from User3;
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