Rownum:
- Rownum is pseudo column and behave like table column.
- It having temporary value.
- It assign number to each row in table at time of selection.
rownum has value < ,<= value it can't worked with > value
Row-id:
when we are inserting data into table Oracle server automatically generates an unique
identification number for identifying record uniquely.
The Main Difference between Rownum and Row-id is
Rownum is temporary values where Row-id having fixed valued it cannot changed.
Some Example:
SQL> select * from t1;
SNO NAME ADDRESS
---------- ---------- ----------
1 kunal nagar
21 sachin parbhani
11 vabhaiv satara
44 jags daund
SQL> select * from t1 minus (select * from t1 where rownum <=(select count(*)-1 from t1));
SNO NAME ADDRESS
---------- ---------- ----------
44 jags daund
SQL> select * from t1 minus (select * from t1 where rownum <=(select count(*)-2 from t1));
SNO NAME ADDRESS
---------- ---------- ----------
11 vabhaiv satara
44 jags daund
SQL> select rowid,rownum,sno,name from t1;
ROWID ROWNUM SNO NAME
------------------ ---------- ---------- ----------
AAARC0AAEAAAAA/AAA 1 1 kunal
AAARC0AAEAAAAA/AAB 2 21 sachin
AAARC0AAEAAAAA/AAC 3 11 vabhaiv
AAARC0AAEAAAAA/AAD 4 44 jags
SQL>
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