Skip to Content
PostgreSQL 10 Administration Cookbook - Fourth Edition
book

PostgreSQL 10 Administration Cookbook - Fourth Edition

by Simon Riggs, Gianni Ciolli
May 2018
Intermediate to advanced content levelIntermediate to advanced
576 pages
30h 25m
English
Packt Publishing
Content preview from PostgreSQL 10 Administration Cookbook - Fourth Edition

How to do it…

Let's say we want to change the dob column to another data type. Let's try with a simple example first, as follows:

postgres=# ALTER TABLE birthdaypostgres-# ALTER COLUMN dob SET DATA TYPE text;ALTER TABLE

This works fine. Let's just change that back to the integer type so that we can try something more complex, such as a date data type:

postgres=# ALTER TABLE birthdaypostgres-# ALTER COLUMN dob SET DATA TYPE integer;ERROR:  column "dob" cannot be cast to type integer

Oh! What went wrong? Let's try using an explicit conversion with the USING clause, as follows:

postgres=# ALTER TABLE birthday               ALTER COLUMN dob SET DATA TYPE integer               USING dob::integer;ALTER TABLE

This works as expected. Now let's try moving to a date type:

postgres=# ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

PostgreSQL 13 Cookbook

PostgreSQL 13 Cookbook

Vallarapu Naga Avinash Kumar
PostgreSQL 9 Administration Cookbook - Second Edition

PostgreSQL 9 Administration Cookbook - Second Edition

Simon Riggs, GIANNI CIOLLI, Hannu Krosing, Gabriele Bartolini

Publisher Resources

ISBN: 9781788474924Supplemental Content