Hi, Is It possible to add new column in table after checking whether column already exists or not?Ap

Shama_Singh

Hi, Is It possible to add new column in table after checking whether column already exists or not?Appreciate your help. Thank you.

[Deleted User]

It wasn't clear if you were trying to do this manually or programmatically. There's no function to test for exists, you'd have to use "\d tablename" or parse the results of "select * from tablename limit 0" to check for the column. In recent versions you can add a column to a table. See alter table in the sql guide for more details. Here's an example.

=> \d testaddcol
                                      List of Fields by Tables
 Schema |   Table    | Column |    Type     | Size | Default | Not Null | Primary Key | Foreign Key
--------+------------+--------+-------------+------+---------+----------+-------------+-------------
 public | testaddcol | c1     | int         |    8 |         | f        | f           |
 public | testaddcol | c2     | varchar(20) |   20 |         | f        | f           |
(2 rows)

=> select * from testaddcol;
 c1 | c2
----+-----
  2 | two
  1 | one
(2 rows)

=> alter table testaddcol add column c3 timestamp default '2014-01-01';
ALTER TABLE
ndw=> \d testaddcol
                                                  List of Fields by Tables
 Schema |   Table    | Column |    Type     | Size |             Default              | Not Null | Primary Key | Foreign Key
--------+------------+--------+-------------+------+----------------------------------+----------+-------------+-------------
 public | testaddcol | c1     | int         |    8 |                                  | f        | f           |
 public | testaddcol | c2     | varchar(20) |   20 |                                  | f        | f           |
 public | testaddcol | c3     | timestamp   |    8 | '2014-01-01 00:00:00'::timestamp | f        | f           |
(3 rows)

=> select * from testaddcol;
 c1 | c2  |         c3
----+-----+---------------------
  2 | two | 2014-01-01 00:00:00
  1 | one | 2014-01-01 00:00:00
(2 rows)

I hope it helps.