Query to add a column in between existing cols of a table?

Question

HI All,
I have two questions.
1. Query to add a column in between existing cols of a table? (not at the end. This is view of an order of output fields in a report)
2. How do I swap the contents of two columns in a table. Suppose in a table tab there are 2 cols , col1,col2 populated with some data.
I need a query(probably) to swap the col1 and col2 values . NOT AS A RESULT SET, BUT IT NEEDS TO GET CHANGED IN THE TABLE.
Please help !

Answer 1

> 1. Query to add a column in between existing cols of
a table? (not at the end. This is view of an order of
output fields in a report)
Not really sensible ito DBMS - it does not care how you want to view the data. The sequence and formats of columns are what you/the application need to specify in the SQL's projection clause.
Also keep in mind to achieve this, the DBMS will need to rewrite the entire table to fit this new column in-between existing columns. This is not the best of ideas.
The projection of rows is dealt with SQL statements - not with the physical storage implementation.
> 2. How do I swap the contents of two columns in a
table. Suppose in a table tab there are 2 cols ,
col1,col2 populated with some data.
I need a query(probably) to swap the col1 and col2
values . NOT AS A RESULT SET, BUT IT NEEDS TO GET
CHANGED IN THE TABLE.
This seems to work:
SQL> create table foo_tab( c1 varchar2(10), c2 varchar2(10) );
Table created.
SQL> insert into foo_tab select TO_CHAR(rownum), TO_CHAR(object_id) from user_objects where rownum < 11;
10 rows created.
SQL> commit;
Commit complete.
SQL> select * from foo_tab;
C1 C2
1 55816
2 55817
3 55818
4 55721
5 105357
6 105358
7 105359
8 105360
9 105361
10 60222
10 rows selected.
SQL> update foo_tab set c1=c2, c2=c1;
10 rows updated.
SQL> select * from foo_tab;
C1 C2
55816 1
55817 2
55818 3
55721 4
105357 5
105358 6
105359 7
105360 8
105361 9
60222 10
10 rows selected.
SQL>