1)rownum不是表的字段。 For each row returned by a query, the ROWNUM pseudocolumn returns a number indicating the order in which Oracle selects the row from a table or set of joined rows.
2)如果不用表的别名,就不知道是t表的rownum还是d表的rownum
SQL> select 1 from (select rownum r from emp) where r<=1; 1 ---------- 1楼主基础还是不扎实
For each row returned by a query, the ROWNUM pseudocolumn returns a number indicating the order in which Oracle selects the row from a table or set of joined rows.
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1楼主基础还是不扎实