MERGE
You can
use merge command to perform insert and update in a single command.
Ex:
SQL> Merge into student121
s1
Using (select *From student122) s2
On(s1.no=s2.no)
When matched then
Update set marks = s2.marks
When not matched then
Insert (s1.no,s1.name,s1.marks)
Values(s2.no,s2.name,s2.marks);
In the above
the two tables are with the same structure but we can merge different structured
tables also but the datatype of the columns should match.
Assume that student121
has columns like no,name,marks and student122 has columns like no,
name, hno,
city.
SQL> Merge into student121
s1
Using (select *From student122) s2
On(s1.no=s2.no)
When matched then
Update set marks = s2.hno
When not matched then
Insert (s1.no,s1.name,s1.marks)
Values(s2.no,s2.name,s2.hno);
