Are PostgreSQL column names case-sensitive?

Question

I have a db table say, persons in Postgres handed down by another team that has a column name say, \"first_Name\". Now am trying to use PG commande

Answer 1

All identifiers (including column names) that are not double-quoted are folded to lower case in PostgreSQL. Column names that were created with double-quotes and thereby retained upper-case letters (and/or other syntax violations) have to be double-quoted for the rest of their life: ("first_Name")

So, yes, PostgreSQL column names are case-sensitive:

SELECT * FROM persons WHERE "first_Name" = 'xyz';

Also fix the incorrect double-quotes around 'xyz'. Values (string literals) are enclosed in single quotes.

Read the manual here.

My standing advice is to use legal, lower-case names exclusively so double-quoting is not needed.