select (select b.field from
(select field from table1 where table1.column = table2.column) b
) c
(select field from table1 where table1.column = table2.column) b
) c
from 表2 ;
For example, such a two-level nesting will report an error, and the error will be reported as follows in Table 2. Column : invalid identifier, after querying the document:
The explanation given by oracle: Test statement select (select * from (select a.dummy from dual a where a.dummy = dual.dummy)) from dual;
Call this to query whether the version corresponding to your own oracle database supports this writing method.
Discussion address for foreigners: https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1853075500346799932#185916940034636142