select (select max(object_id) from test2 b where b.object_id =a.object_id) from test1 a
变成如下：
10053中：
变成如下：
点击(此处)折叠或打开
-
SELECT VW_SSQ_1.MAX_OBJECT_ID
-
FROM (SELECT MAX(B.OBJECT_ID) "MAX_OBJECT_ID", B.OBJECT_ID "ITEM_1"
-
FROM TEST2 B
-
GROUP BY B.OBJECT_ID) "VW_SSQ_1",
-
TEST1 A
- WHERE VW_SSQ_1.ITEM_1(+) = A.OBJECT_ID
10053中：
点击(此处)折叠或打开
-
JE: Considering Join Elimination on query block SEL$C772B8D1 (#1)
-
*************************
-
Join Elimination (JE)
-
*************************
-
SQL:******* UNPARSED QUERY IS *******
-
SELECT "VW_SSQ_1"."MAX(OBJECT_ID)" "(SELECTMAX(OBJECT_ID)FROMTEST2" FROM (SELECT MAX("B"."OBJECT_ID") "MAX(OBJECT_ID)","B"."OBJECT_ID" "ITEM_1" FROM "SYS"."TEST2" "B" GROUP BY "B"."OBJECT_ID") "VW_SSQ_1","SYS"."TEST1" "A" WHERE "VW_SSQ_1"."ITEM_1"(+)="A"."OBJECT_ID"
-
SQL:******* UNPARSED QUERY IS *******
-
SELECT "VW_SSQ_1"."MAX(OBJECT_ID)" "(SELECTMAX(OBJECT_ID)FROMTEST2" FROM (SELECT MAX("B"."OBJECT_ID") "MAX(OBJECT_ID)","B"."OBJECT_ID" "ITEM_1" FROM "SYS"."TEST2" "B" GROUP BY "B"."OBJECT_ID") "VW_SSQ_1","SYS"."TEST1" "A" WHERE "VW_SSQ_1"."ITEM_1"(+)="A"."OBJECT_ID"
- Query block SEL$C772B8D1 (#1) unchanged
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/29990276/viewspace-1779246/ ，如需转载，请注明出处，否则将追究法律责任。
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