UPDATE EMP
SET DEPTNUM = 15, MGRNUM=$MGRNUM WHERE EMPNUM = 100;
(a) 分段透明性(级别1)
位置透明:
SELECT NAME,SAL,TAX INTO $NAME,$SAL,$TAX FROM EMP1
WHERE EMPNUM = 100 ;
SELECT MGRNUM INTO $MGRNUM FROM DEPT2
WHERE DEPTNUM = 15 ;
DELETE EMP1 WHERE EMPNUM = 100; DELETE EMP2 WHERE EMPNUM = 100;
INSERT INTO EMP3(EMPNUM,SAL,TAX,DEPTNUM); (100,$NAME,15 );
INSERT INTO EMP4(EMPNUM,SAL,TAX,MGRNUM); (100,$SAL,$TAX ,$MGRNUM);
(b) 位置透明性(级别2) 本地映射透明:
SELECT NAME,SAL,TAX INTO $NAME,$SAL,$TAX FROM EMP1 AT SITE1 WHERE EMPNUM = 100 ;
SELECT MGRNUM INTO $MGRNUM FROM DEPT2 AT SITE2 WHERE EMPNUM = 15‘ ;
DELETE EMP1 AT SITE1 WHERE EMPNUM =100; DELETE EMP1 AT SITE5 WHERE EMPNUM =100; DELETE EMP2 AT SITE2 WHERE EMPNUM =100;
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DELETE EMP2 AT SITE6 WHERE EMPNUM =100; INSERT INTO EMP3(EMPNUM,NAME,DEPTNUM); AT SITE3:(100,$NAME,15 );
INSERT INTO EMP3(EMPNUM,NAME,MGRNUM); AT SITE7:(100,$NAME ,15);
INSERT INTO EMP4(EMPNUM,SAL,TAX,MGRNUM); AT SITE4:(100,$SAL,$TAX,$MGRNUM); INSERT INTO EMP4(EMPNUM,SAL,TAX,MGRNUM); AT SITE8:(100,$SAL,$TAX,$MGRNUM);
(C) 本地映射透明性(级别3)
图4.2 不同级别分布透明性下的更新应用。
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