# Migration file: Default value for timestamp column
**URL:** https://discourse.rom-rb.org/t/migration-file-default-value-for-timestamp-column/702
**Category:** Uncategorized
**Created:** [July 5, 2025, 3:03pm UTC](https://discourse.rom-rb.org/t/migration-file-default-value-for-timestamp-column/702 "2025-07-05T15:03:36Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@jignesh](https://discourse.rom-rb.org/u/jignesh)
#### Post date: [July 5, 2025, 3:03pm UTC](https://discourse.rom-rb.org/t/migration-file-default-value-for-timestamp-column/702/1 "2025-07-05T15:03:36Z")
In my Hanami 2.2 app I have a migration file having following code:
```auto
# frozen_string_literal: true
ROM::SQL.migration do
# Add your migration here.
#
# See https://guides.hanamirb.org/v2.2/database/migrations/ for details.
change do
create_table :orders do
primary_key :id
foreign_key :item_id, :items, null: false, default: 0
column :quantity, :integer, null: false, default: 1
column :created_at, :timestamp, null: false
column :updated_at, :timestamp, null: false
end
end
end
```
I want to set default value as dynamic current-time for timestamp columns. So I used `default: 'now()'` for the timestamp column.
But with that in DB table structure default value found set was like following `'2025-07-05 19:23:49.730244'::timestamp without time zone` which is unintended.
Following are the additional findings:
- When using `default: 'CURRENT_TIMESTAMP'` and running the migration getting following error:
```auto
Caused by:
PG::InvalidDatetimeFormat: ERROR: invalid input syntax for type timestamp: "CURRENT_TIMESTAMP" (PG::InvalidDatetimeFormat)
LINE 1: ...EFAULT 1 NOT NULL, "created_at" timestamp DEFAULT 'CURRENT_T...
^
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:171:in 'PG::Connection#exec'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:171:in 'block in Sequel::Postgres::Adapter#execute_query'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/extensions/error_sql.rb:63:in 'Sequel::ErrorSQL#log_connection_yield'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:171:in 'Sequel::Postgres::Adapter#execute_query'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:159:in 'block in Sequel::Postgres::Adapter#execute'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:136:in 'Sequel::Postgres::Adapter#check_disconnect_errors'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:159:in 'Sequel::Postgres::Adapter#execute'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:532:in 'Sequel::Postgres::Database#_execute'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:348:in 'block (2 levels) in Sequel::Postgres::Database#execute'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:555:in 'Sequel::Postgres::Database#check_database_errors'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:348:in 'block in Sequel::Postgres::Database#execute'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/connection_pool/timed_queue.rb:85:in 'Sequel::TimedQueueConnectionPool#hold'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/database/connecting.rb:283:in 'Sequel::Database#synchronize'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/postgres.rb:348:in 'Sequel::Postgres::Database#execute'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/database/query.rb:50:in 'Sequel::Database#execute_dui'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/database/query.rb:43:in 'Sequel::Database#execute_ddl'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/database/schema_methods.rb:710:in 'Sequel::Database#create_table_from_generator'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/database/schema_methods.rb:211:in 'Sequel::Database#create_table'
/home/jignesh/.rvm/gems/ruby-3.4.4@my_app/gems/sequel-5.93.0/lib/sequel/adapters/shared/postgres.rb:468:in 'Sequel::Postgres::DatabaseMethods#create_table'
/..../my_app/config/db/migrate/20250627002000_create_orders.rb:6:in 'block (2 levels) in '
```
- When using `default: Sequel::CURRENT_TIMESTAMP` and running the migration, in DB table structure default value found set is `CURRENT_TIMESTAMP` which is correct.
Can anybody please explain what difference using `Sequel::CURRENT_TIMESTAMP` is making compared to using the string literal `CURRENT_TIMESTAMP`?
Note:
Found about the Sequel constant from [Default Sequel::CURRENT\_TIMESTAMP vs Safe Prepared Statements · Issue #1168 · jeremyevans/sequel · GitHub](https://github.com/jeremyevans/sequel/issues/1168#issue-147085951); that post I found
while searching for the error “PG::InvalidDatetimeFormat…” I mentioned before.
Thanks.
---
### Author:  [@alassek](https://discourse.rom-rb.org/u/alassek)
#### Post date: [July 7, 2025, 9:23pm UTC](https://discourse.rom-rb.org/t/migration-file-default-value-for-timestamp-column/702/2 "2025-07-07T21:23:47Z")
The string literal doesn’t work because `CURRENT_TIMESTAMP` is not a string literal, it is a function call. So this generates an invalid SQL statement.
If you inspect `Sequel::CURRENT_TIMESTAMP`, you will see that it is an instance of `Sequel::SQL::Constant`.
An alternate way to declare a function call in a migration:
```ruby
column :created_at, :timestamp, null: false, default: Sequel.lit("CURRENT_TIMESTAMP")
```
Using a SQL literal inserts the string as-is into the query, which will also be interpreted correctly by the database. Essentially, you’re running afoul of the protection against SQL-injection that ensures regular string types are always correctly quoted.