Are PostgreSQL column names case-sensitive?

Unmasking PostgreSQL's treatment of column names

Living in the lowercase world

When you don't use quotes, PostgreSQL:

• Transforms identifiers to lowercase:

  -- Firstname? Never met him, did you mean 'firstname'?
  SELECT firstname FROM people;
  

• Keeps identifiers and strings completely separate:

  -- Whoa! 'FirstName' is a string, not a column, buddy.
  SELECT 'FirstName' FROM people;
  

Embracing case sensitivity

When you do use double quotes:

• PostgreSQL follows your exact case and characters:

  -- Finally, "FirstName" has arrived!
  SELECT "FirstName" FROM people;
  

• Requires consistent quoting in every reference, which might turn into an exercise of accurate memory!

Nailing it: The recommended way to name columns

Sticking to lowercase

Using only lower-case names:

• Eliminates the need to type quotes:

  -- Cool as cucumber! No case worries.
  SELECT first_name FROM people;
  

• Makes your SQL queries more readable and less error-prone.

Steering clear of reserved words

Staying away from SQL reserved words:

• Avoids potential syntax conflicts:

  -- 'user'... hmm, haven't I seen you somewhere?
  SELECT user FROM accounts;
  

• Promotes use of more descriptive and unambiguous identifiers.

Application & portability considerations

Impact on application development

Maintaining consistency: Inconsistencies can lead to errors in application development, especially with ORMs:

# Assumes the accurate spelling and case is 'first_name'.
Person.objects.get(first_name='John') 


Handling database migrations

Transferring or transitioning databases can sometimes turn into a puzzle game. To modify column names to lowercase:

-- Changing lives, one column at a time.
ALTER TABLE "People" RENAME COLUMN "FirstName" TO first_name;


Understanding SQL standards

PostgreSQL is like the rebellious teenager of SQL databases:

• SQL is set to default fold unquoted names to upper case.
• But PostgreSQL, being the cool kid, folds to lower case.

Dealing with literal constants vs. identifiers

• Wrap string literals or constants in single quotes:

  -- Who's 'John'? Oh! You meant value 'John' for 'first_name'.
  SELECT * FROM people WHERE first_name = 'John'; 
  

• Reserve double quotes for exact-case column names:

  -- Please reserve the seat for "FirstName".
  SELECT "FirstName" from people;
  