Oracle Faq (How to change the column name and order of a table in ORACLE)_PHP tutorial

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Anyone who has used ORACLE knows that changing the column names and order of tables in ORACLE is a very cumbersome task. Here is a simple method for you.

SQL> select object_id from all_objects where owner='SCOTT' and object_name='T1';

OBJECT_ID
----------
6067
SQL> select obj#,col#,name from sys.col$ where obj#=6067;

OBJ# COL#
---------- ---- ------
NAME
------------------------------------- -----------------------
6067 1
ID

6067 2
NAME

SQL> update sys.col$ set name='NEW_ID' ,col#=3 where obj#=6067 and name='ID';

1 row updated.

SQL> update sys .col$ set name='MY_NAME',col#=1 where obj#=6067 and name='NAME';

1 row updated.

SQL> update sys.col$ set col#=2 where obj#=6067 and col#=3;

1 row updated.

SQL> commit;

Commit complete.

SQL> select * from scott.t1;

ID NAME
---------- --------------------
3 cheng
2 yong
1 xin
2 gototop
1 topcio
2 yongxin
1 cyx

7 rows selected.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 128159368 bytes
Fixed Size 732808 bytes
Variable Size 117440512 bytes
Database Buffers 8388608 bytes
Redo Buffers 1597440 bytes
Database mounted.
Database opened.
SQL> select * from scott.t1;

MY_NAME NEW_ID
-------------------- ----------
cheng 3
yong 2
xin 1
gototop 2
topcio 1
yongxin 2
cyx 1

7 rows selected.

So far we have SCOTT.T1 The column names and order in the table have been given. If you only want to change the order but not the column names, you only need to perform UPDATE again. The reason why it cannot be completed at once is because COL# and NAME in SYS.COL$ are both UNIQUE.

Although this method has certain risks, the effect is obvious for particularly large tables, while using the general method will require more storage space, rollback segments and time overhead.​

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