Editing Default Values of a column / table in postgres using Pgadmin4 - postgresql

How do I set the default values of a column/table in pgadmin4 if a value isn't inserted? I would like it to be 0 instead of null.

You can use ALTER TABLE ... ALTER COLUMN.
ALTER TABLE elbat
ALTER COLUMN nmuloc
SET DEFAULT 0;

Related

Changing maxvalue of sequence which is defined inside table in db2

Hi I want to Change maxvalue of sequence which is defined inside table in db2.
Alter sequence "sequencename" is not working
Alter sequence is not working
A Sequence is external to a table.
Are you actually trying to update an identity column?
ALTER TABLE MY_TABLE ALTER COLUMN MYCOLUMN SET MAXVALUE MY_MAX_VALUE

Postgres set auto increment counter to a fixed value

I want to set primary value to start with 1000 in postgres.
i know a command in mysql
ALTER TABLE tablename AUTO_INCREMENT = 1000
how to write the above mysql command in postgres ?
identity (and the somewhat outdated serial) columns are based on sequences.
You can set the sequence associated with such a column using setval()
select setval(pg_get_serial_sequence('table_name', 'column_name'), 1000);

PostgreSQL add auto increment to empty ID column

I create table in PostgreSQL but I forgot to add auto increment.
How to alter empty Id column in Postgres to add auto increment?
Starting with Postgres 10 it's recommended to use identity columns for this.
You can turn an existing column into an identity column using an ALTER TABLE:
alter table the_table
alter id add generated always as identity;
If you already have data in the table, you will need to sync the sequence:
select setval(pg_get_serial_sequence('the_table', 'id'), (select max(id) from the_table));
You will need to create a sequence owned by that column and set that as the default value.
e.g.
CREATE TABLE mytable (id int);
CREATE SEQUENCE mytable_id_seq OWNED BY mytable.id;
ALTER TABLE mytable ALTER COLUMN id SET DEFAULT nextval('mytable_id_seq');

PostgreSQL - ALTER column data type from integer to integer array

Kindly help to modify a column of type integer to integer array:
I had created a table with a column content_id of type integer. then I tried to change the content_id(integer) to integer[](integer array) but its showing error as displayed:
TestDatabase=# ALTER TABLE tbl_handset_content ALTER COLUMN content_id TYPE integer[];
ERROR: column "content_id" cannot be cast to type "pg_catalog.int4[]"
Regards,
Sravan
Try this (column test_id is of type INTEGER before alter takes place). PostgreSQL 8.4.
ALTER TABLE test.test_id
ALTER COLUMN test_id TYPE INTEGER[]
USING array[test_id]::INTEGER[];
This worked better for me!
ALTER TABLE schema.table
ALTER COLUMN column
DROP DEFAULT;
ALTER TABLE schema.table
ALTER COLUMN column TYPE INTEGER[]
USING array[column]::INTEGER[];
ALTER TABLE schema.table
ALTER COLUMN column SET DEFAULT '{}';

Postgres: Reduce varchar size and truncate

I currently have a Postgres 8.4 database that contains a varchar(10000) column. I'd like to change this into a varchar(255) and truncate any data that happens to be too long. How can I do this?
Something like ALTER TABLE t ALTER COLUMN c TYPE VARCHAR(255) USING SUBSTR(c, 1, 255)
1) Update the column data using a substring method to truncate it
update t set col = substring(col from 1 for 255)
2) Then alter the table column
alter table t alter column col type varchar(255)
Docs here http://www.postgresql.org/docs/8.4/static/sql-altertable.html
BEGIN;
UPDATE table SET column = CAST(column as varchar(255));
ALTER TABLE table ALTER COLUMN column TYPE varchar(255); --not sure on this line. my memory is a bit sketchy
COMMIT;