1---
2title: Use Lowercase Identifiers for Compatibility
3impact: MEDIUM
4impactDescription: Avoid case-sensitivity bugs with tools, ORMs, and AI assistants
5tags: naming, identifiers, case-sensitivity, schema, conventions
6---
7 
8## Use Lowercase Identifiers for Compatibility
9 
10PostgreSQL folds unquoted identifiers to lowercase. Quoted mixed-case identifiers require quotes forever and cause issues with tools, ORMs, and AI assistants that may not recognize them.
11 
12**Incorrect (mixed-case identifiers):**
13 
14```sql
15-- Quoted identifiers preserve case but require quotes everywhere
16CREATE TABLE "Users" (
17  "userId" bigint PRIMARY KEY,
18  "firstName" text,
19  "lastName" text
20);
21 
22-- Must always quote or queries fail
23SELECT "firstName" FROM "Users" WHERE "userId" = 1;
24 
25-- This fails - Users becomes users without quotes
26SELECT firstName FROM Users;
27-- ERROR: relation "users" does not exist
28```
29 
30**Correct (lowercase snake_case):**
31 
32```sql
33-- Unquoted lowercase identifiers are portable and tool-friendly
34CREATE TABLE users (
35  user_id bigint PRIMARY KEY,
36  first_name text,
37  last_name text
38);
39 
40-- Works without quotes, recognized by all tools
41SELECT first_name FROM users WHERE user_id = 1;
42```
43 
44Common sources of mixed-case identifiers:
45 
46```sql
47-- ORMs often generate quoted camelCase - configure them to use snake_case
48-- Migrations from other databases may preserve original casing
49-- Some GUI tools quote identifiers by default - disable this
50 
51-- If stuck with mixed-case, create views as a compatibility layer
52CREATE VIEW users AS SELECT "userId" AS user_id, "firstName" AS first_name FROM "Users";
53```
54 
55Reference: [Identifiers and Key Words](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS)
56